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PAC SOEM-4 Factory Integration Adapter

Connect a new car stereo or amps to factory vehicle wiring with this universal 4-channel line output converter

Item #: 127SOEM4

61 Reviews

This item is no longer available.

Original Price: $29.99

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Want to add amplifiers to your factory stereo, but finding it hard to do with today's complicated factory systems? PAC's SOEM-4 4-channel line output converter gives you lots of options, including:

  • connecting an aftermarket radio to a common-ground speaker system;
  • converting a factory radio's speaker-level outputs to a preamp-level signal that can be connected to aftermarket amplifiers;
  • adding aftermarket amplifiers to factory premium systems (Bose®, JBL, etc.);
  • connecting an aftermarket radio to a factory amplifier.

The SOEM-4 features independent level controls for each of its 4 channels, so you can adjust output for any amplifier. Special circuitry minimizes extraneous noise, and prevents any load from being added to your system. The adapter also features remote turn-on outputs for amps and power antennas. Its internal transformer is isolated, ensuring optimal sound quality.

Installation Note: This adapter measures 3-1/16"W x 1-3/8"H x 6"D. You may have to find another location for mounting if it won't fit behind the radio in your dash.

Note: Most vehicles will require additional installation parts — please identify your vehicle if you haven’t done so. You can also call an Advisor for more information.

Product Highlights:

  • 4-channel input and output wiring
  • independent level controls
  • 12-volt amplifier turn-on trigger wire
  • frequency response: 20-20,000 Hz
  • isolated transformer for optimal sound and performance
  • maintains correct phasing
  • warranty: 1 year
  • Our 60-day money-back guarantee

PAC SOEM-4 Factory Integration Adapter Reviews

Average Customer Review:

61 Reviews

Works flawlessly, awesome product

Written by: Jay from Franklin, KY on April 30, 2014

Crutchfield Customer Review (What's this?)

This PAC unit is perfect for hooking up an amp to a factory stereo that don't have RCA line outputs and no remote turn on switch wire. Have 2000 mustang w/factory stereo & CD deck and speakers. Mounted the PAC in my trunk & hooked my factory speaker wires into wired harness on PAC's input side & the PAC's +&- into my amps +&- and the PAC's remote wire into amps remote. PAC's wire harness wires aren't but about 8" long so you'll need some light gauge wire to run to your speakers & +&- & remote to amp. On the PAC's output I used the RCA harness to run into my amp. I didn't want to cut into my factory stereo wire harness so that's why I mounted the PAC in my trunk. Because of my amp being back there my +&- was already ran which is all you need for this to work other than remote wire which goes from PAC to amp. It was very simple to hook up. If you have aftermarket stereo I'd recommend installing PAC under dash or beside deck. The case is hard to get back together if you have to take it apart & knobs will fall out. I used a tiny drop of super glue on bottom of knobs and slid back in, but only do that if u take PAC apart so u don't get glue on gain adjustments so they don't get stuck in wrong position. I left gains on mine turned all the way up. Put the PAC's cover back on carefully paying attention to the right places to squeeze so it'll go back together. It will take a few min. to snap together right. But I really had no trouble. PAC works flawlessly. Very easy installation.

Pros: Absolutely no whining noises, works flawlessly, it turns PAC & amp on when audio signal is detected and your amp & PAC off when your radio is turned off. Comes with wired output harness also for non-RCA applications. Uses almost no power so u can hook it directly into your amps + & - if you want to without having to go up on fuse amperage. Excellent instant customer service if you have any installation questions. Best customer support of any customer supports out there. These guys are on point.

Cons: If you have to take it apart which I would suggest. To glue the knobs in so they don't fall out. But if u turn the gains all way up & never want to adjust em U don't have to bother. But if u turn the PAC upside down the knobs will most likely fall out. The case pops right off but is hard to get back together but if u don't handle it like a gorilla, take your time & do it right, it will go back together. It just might take of little effort & patience & squeezing the case in the right places.

Alternator whine noise? Do this....

Written by: Mike from Ohio on March 2, 2014

Crutchfield Customer Review (What's this?)

Like a lot of folks I am using this on a Miata that previously had the BOSE system. I got everything all back together and working great, then started the car and noticed engine noise coming through the speakers. The higher the engine would rev, the higher pitched the noise. After trying many different things with ground wires, noise filters, etc, I finally discovered that if I adjusted the levels on this thing to the maximum, the noise went completely away. So if you are getting engine noise, try adjusting the levels.

I am deducting a star because right after adjusting the levels, the little screw level adjuster fell off. Not a problem since I had things adjusted when it fell off, but it's a sign that it's a little cheaply made. But it works, and it lives hidden in the dash, so I really don't care.

Pros: Connects stereo to BOSE system

Cons: Cheaply made, let in engine noise until I got the levels adjusted.

Good product

Written by: Bill from Waterbury,ct on January 19, 2014

2005 Hyundai Santa Fe
Crutchfield Customer Review (What's this?)

Had to call to figure it out but the tech team is awesome and really made it simple to understand. Once they gave me the instructions it was really simple to install. I wired it up and was perfect first shot. Great product

Pros: Easy to install Worked excellent

Cons: Had to call to get more specifics.

PAC SOEM-4 - 2004 Mazda/Bose

Written by: BWags from Narragansett, RI on December 29, 2013

2004 Mazda Miata
Crutchfield Customer Review (What's this?)

I bought this to install a new Kenwood head unit in a 2004 Mazda Miata with an existing Bose system. Absent a complete "Bose-ectomy" this little box is a necessary evil to connect any aftermarket head unit to Mazda's existing Bose amp and its really strange 0.5 ohm speaker set up. It adds another layer of complication to patching into your car's wiring harness. If you're like me and solder all of your connections, then you have to be patient, organized and careful to line up your head unit's harness, the adapter harness and your vehicle's harness because the instructions that come with this thing SUCK. Find the Crutchfield number before you start because you're going to need it. You also need some extra wire to create extensions for the wires that do not go through the PAC unit, so that you wind up with a harness that's all one length and long enough to stash this brick in an empty spot behind your dash. If you do not add wire, the wires that go straight from your head unit to your factory harness will be half the length of the wires that go through the PAC and will hold the PAC brick so close to the unit that you will have very limited options for finding a spot to stash the PAC behind the radio. That being said - the thing WORKS. My 2004 MIata's Bose speakers now sound awesome thanks to the new Kenwood KDC-997 headunit that the PAC SOEM-4 allowed me to install.

Pros: It works - it lets you connect a quality aftermarket head unit into your non-standardized OEM amps and speakers.

Cons: It's way more difficult to install than it needs to be. Very poor instructions, but a call to Crutchfield got me straightened out. Needs to include some extra harness wires in various colors in 18" lengths to lengthen the wires that do not through the PAC unit (e.g. antenna, ground etc.) so that the harness with the PAC wired in-line is all one length and you have some flexibility in finding a place to stash the box behind the dash.

Great product

Written by: Joe Goz from Orland Park, IL on October 21, 2013

2005 Acura MDX
Crutchfield Customer Review (What's this?)

Really boosted my factory speakers

Pros: Provided a big boost to existing Bose system in vehicle, most wires match easily, quick phone call to Crutchfield resolved any issues

Cons: Not all wires match exactly & had to decide them by calling Crutchfield


Written by: Mike from North Carolince on October 19, 2013

Beware, buyers, if your instructions state you must install this hunk of crud in order to use your factory amp. In this case, you must wire this thing (mine came with instructions for 3 GM cars, which was helpful for my BMW) between your head unit and the factory plug. This means it has to fit in the dash, which would not be a problem if it were not the size of a brick. This pictures do not tell the story. It is, pay attention here: 3.5 inches wide, 6 inches long and 1.5 inches deep. Right, it is HUGE and a HUGE PAIN to try to stuff in an already crowded dash.

To top it off, its construction reminds me of a kid's cheap electronics hobby project. FROM 1972! In order to use it, you probably will have to snap (yes, snap) it apart to change the wiring (it comes with RCA and speaker wires, depending on whether you will use it for an amp or like I needed it, to splice into the HU wires). Of course, it came with the other ones pre-installed, which is usually my luck. After I changed the crappy wire plug, it would no longer SNAP fully back together, such is the quality of this masterpiece.

Oh, and after I had it in, it worked like - you guessed it - JUNK. It caused distortion of the signal at anything over moderated volume. No, my components were proven fine before, I know they worked. I cut the piece of junk out, and spent the next 4 hours bypassing my factory amp to use the HU alone for now. Works great now. Thanks for the wasted day.

1 star is the lowest allowed.

Pros: It did not explode.

Cons: It did not explode, for details, read above review.

Does it's job with short comings

Written by: ErnieH from Charlestow, NH on October 11, 2013

Crutchfield Customer Review (What's this?)

Technical info regarding proper wiring for different vehicles is not through and very vague leading to confusion, wasted time and calls to the great support team at Crutchfield. Also, when mine arrived two of the control knobs for the levels adjustment had fallen out during shipment so I had to apply a touch of super glue to hold them in place (only applied to the very end of the shaft so as to not mistakenly weld the sleeve that must remain free to turn for adjustments).

Pros: It does do what it is meant to do but ! - see the "Cons" comments.

Cons: Poor Technical info regarding proper wiring for different vehicles. Poor quality control.

PAC SOEM-4 Adapter review

Written by: TomS from Snohomish, WA on October 10, 2013

2004 Mazda Miata
Crutchfield Customer Review (What's this?)

Seems to work OK. Needed Crutchfield Tech Support to confirm the wiring, as the instructions are not clear what is needed and what isn't.

Pros: Works fine and with Crutchfield help, all went together and worked first time out the gate.

Cons: No instructions regarding tuning setup. Vague wiring instructions, but just collect your questions and call Crutchfield. They have this stuff down.

Good solution for using factory amplifier

Written by: Levi from Denver, CO on September 20, 2013

Crutchfield Customer Review (What's this?)

I needed this unit to make the Alpine CD-receiver I bought compatible with the factory amplifer in my 2005 Hyundai Santa Fe. I had both units professionally installed by Car Toys. The PAC SOEM-4 does the job it is intended to do. However, there is a slight background humm in the speakers in my SUV. Car Toys had to readjust the dials (gain screws) to lower the background humm to a tolerable level. You cannot set the dials for maximum headroom extention and sound fidelity when using an unmatched factory amplifier (the one used by my previous Monsoon Head Unit), because it produced too loud of a background humm. So this PAC SOEM-4 is like a band-aid approach to making an aftermarket head unit (Alpine CD-receiver) compatible with an existing factory amplifier. (which is what my Hyundai has). You DO NEED this PAC SOEM-4 to make the aftermarket head unit work in Hyundais and many other vehicle makes. The only other solution is to also buy an new amplifer (aftermarket). I did not want to have that extra expense.

Pros: Good, low cost solution to making a new head unit (car stereo CD receiver) work with my vehicle's factory amplifier (to make them compatible with each other). It works.

Cons: Tricky to adjust dials and fine tune. They are very sensitive. Most people will need a professional technician to install this (myself included) along with a new head unit. Also, this unit causes a slight background humm (or hiss) to be heard in my vehicle's speakers. It will not allow you to obtain maximum sound quality (headroom extention, dynamic range and fidelity) from a new (aftermarket) CD-receiver head unit; which will be a small sacrifice for most people.

PAC SOEM-4 Factory Integration Adapter

Written by: Anonymous from Warren, ohio on August 18, 2013

2000 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Directions to install this unit were horrendous. Very bulky unit




Written by: GaryE from Van Nuys, CA on August 13, 2013

Crutchfield Customer Review (What's this?)

This product was half off with my purchase of a receiver. It made the install easy for the tech.

Pros: It's half off with purchase!!!

Cons: Don't have any!

What can I say it worked as advertised

Written by: sunsetalan from Fairport NY on July 17, 2013

1992 BMW 535I
Crutchfield Customer Review (What's this?)

Well documented and well built with easy to install instructions

Pros: Well documented

Cons: A bit on the bulky side

Not required for my installation.

Written by: Ron H. from New Bern, NC on July 12, 2013

1984 Volkswagen Vanagon
Crutchfield Customer Review (What's this?)

I can't rate the function of this product since my vehicle does not have an amplifier. It was suggested I needed this product so I bought it. It killed the radio's volume so support suggested I remove it and this fixed my problem. I didn't understand at the time of purchase that this product is for controlling an amplifier. Not for standard installation.




Written by: ShannyJ from Athens, AL on July 6, 2013

Crutchfield Customer Review (What's this?)

It was recommended but I did not need, not use it.

Pros: Good if you have extra speakers, sub spiders.

Cons: Not needed for a standard installation.

It Works For Me

Written by: LKIII from St. Louis on July 4, 2013

2005 Hyundai Santa Fe
Crutchfield Customer Review (What's this?)

I purchased to install a Pioneer FH-X700BT into a 2005 Hyundai Santa Fe with a Monsoon Head Unit originally installed. I still am not sure why I needed this, but Crutchfield said it was a must. I wasn't sure what to do with regards to where it needed to be soldered, and Crutchfield Customer Service shined through on this for me. After one quick phone call, and opening an email they sent right to me I had it connected in no time. Sounds great and feels very sturdy and well made.

Pros: Well Made

Cons: A bit bulky May be difficult to place in dash in some cars

Poor build quality

Written by: D S from APO Germany on July 1, 2013

Crutchfield Customer Review (What's this?)

Although It might help some users, in the end I did not need this part as I do not hook up an amp etc. If I did want to use this, I doubt it would have worked since it literally fell apart when I opened the package! The case will not go back together and a few of the electronic components inside are loose/falling apart - looks like a 5 year old designed and built this.

Pros: none

Cons: wont stay together.

pac soem-4

Written by: Dannie M from Farmingtion Hills, Mi on June 20, 2013

Crutchfield Customer Review (What's this?)

Hello the Pac was a big help i like this and i would recommend it to others.



PAC SOEM-4 Factory Integration Adapter

Written by: Anonymous from Brooklyn ny on May 12, 2013

Crutchfield Customer Review (What's this?)

Installed this item at the recommendation of the Crutchfield rep. Almost caused me to return my entire order. Removed the adapter, and the Jensen that I put in worked wonderfully.



do you need this?

Written by: joey from texas on February 28, 2013

Crutchfield Customer Review (What's this?)

I bought this for my e46 bmw. I did not install it although I wish sometimes I had. This will regulate smoothness in your volume up and down control. Because I didn't install this I have to finesse the volume knob and the steering wheel control volume is even more touchy. Without It i get more volume.

Pros: cheap and will do a few diffrent jobs haveing rca output.

Cons: Dont really need it in most cases.

excellent product at a very good price

Written by: Ruben from Brownsville, TX on February 4, 2013

2001 Oldsmobile Intrigue
Crutchfield Customer Review (What's this?)

I was looking to install an old subwoofer in a new to me vehicle but i didn't want to replace the stock stereo. A friend of mine told me they sell an item (converter) that would help so i went to a local shop to see what was available. the unit they showed me was over $100 and far beyond my budget. i was pleasantly surprised when i found this item on cructhfield's website and at such a low price. the shipping was free and it came in exactly when they said it would. the wiring diagrams are a little vague but this was not my first installation so i trudged on. i mounted the unit to the sub box and made as many of the connections as possible before i placed the sub box, with amp and pac unit in the trunk. after splicing into all the wires as required and figuring out which rca output set was the right one, it worked like a charm.

Pros: very simple unit to solve a very big problem, especially in todays modern vehicles

Cons: vague instructions, you will need splicers and extra wiring on hand.

Sure... Whatever

Written by: Anonymous from Oklahoma City, OK on February 2, 2013

2005 Pontiac Vibe
Crutchfield Customer Review (What's this?)

Used to install a radio in a 05' vibe. It was easy to wire up and does not detract from audio quality, but is built a bit on the cheap side. I took it apart to swap the wiring harness and had to use zip ties to hold together. Is this thing really needed????

Pros: Easy to wire and good audio

Cons: Built cheap. Make sure to have zip ties to hold together, you'll need them.

Good product -- installation trick for BMW E46

Written by: WJB from Minneapolis, MN on January 9, 2013

2005 BMW 3 Series
Crutchfield Customer Review (What's this?)

Sounds very good, easy to set, and pretty easy to wire up and install -- it's a color-coded wire-to-wire match-up, for the most part. For my BMW E46, Arthur the reviewer below is right; take out the entire bracket that holds the stereo and the climate controls below it. On re-installation, I then used some double-sided tape to hold the unit up and away from where the stereo bracket goes back in. Without removing that bracket first, I don't see how you could get it all to fit back in that car's dash. But by removing the bracket, it's not a big deal.



1994 BMW w/JVC Arsenal

Written by: Darin M from Guilford, cT on October 28, 2012

Crutchfield Customer Review (What's this?)

Did not need for installing into 1994 BMW 525i with JVC Arsenal stereo.

Pros: None

Cons: None

Works fine

Written by: Kachi X from St. Paul, MN on October 23, 2012

2006 Acura RSX
Crutchfield Customer Review (What's this?)

Recommended for my bose system and works fine so far.


Cons: Directions is not clear enough with some wires.

Good device

Written by: Vulkrider from Olney Md on October 18, 2012

Crutchfield Customer Review (What's this?)

Used for a Monsoon amp in a Santa Fe. I thought it would be more difficult but after talking to the free tech, i was told I didn't need the power or ground (or anything else on it connected), it was simple. I just connected the speaker wires through it an it worked great.

Pros: Simple, just connect the speaker wires through it.

Cons: Could have been clearer that the other leads did not need connecting.

Rip off

Written by: JamesE from Newport, Wa on October 12, 2012

Crutchfield Customer Review (What's this?)

The PAC unit was included with items they thought I would need to install my radio purchase. There was no room for it in my dash, and I am out the purchase price, as the radio works fine without it. For my next radio I will go to a different retailer.



PAC SOEM-4 Factory Integration Adapter

Written by: Lee from Jacksonville, FL on August 14, 2012

2003 Acura 3.2CL
Crutchfield Customer Review (What's this?)

Bought this because it was recommended by Crutchfield. Instructions for installation are not clear and instructions for use did not exist. I didn't make any adjustments to it but everything seems okay.

Pros: unknown

Cons: poor instructions

re-think your purchase

Written by: Dave from Southern VT on July 25, 2012

1995 Audi 90
Crutchfield Customer Review (What's this?)

The build quality of this device is a little iffy. This device is only needed for those who need to activate the in-speaker amplifiers on car who's manufacturer's thought that would be a good idea. Well it wasn't, and most time those speakers are broken anyway. Consider getting all aftermarket parts so you don't even need this thing. Call a Crutchfield tech if you're unsure, they will be your best resource.



does the job

Written by: RC from Los Angeles, CA on July 21, 2012

Crutchfield Customer Review (What's this?)

4 out of 5 stars... it does what it says in the description... i just hope there is a specific instruction for certain models specially for german cars.. this is not a plug and play adapter, u need to do some adjustments for your liking... u really need this if u have a stock amplifier in ur car... very good device

Pros: Cheap, Good sound for stock bose speakers, subs and amplifier

Cons: Settings of wires, RCA or hard wire could get very big deal in terms of sound quality.. so u have to try both wirings not just because the manual says thats the right way to do. Large

Works on BMW E46 with and without Harmon Kardon

Written by: Arthur from Denver on July 3, 2012

Crutchfield Customer Review (What's this?)

I don't know if it is necessary on a BMW E46 without a Harmon Kardon sound system but it does work with both. I initially had it installed in my E46 325xi because Crutchfield listed it as a required item back then. Worked fine, but I never tried it without. When I got an E46 M3 with HK sound system I transferred it right over with no change in settings or connections. Just unplugged the harness from the old car and plugged it right into the new. Extremely happy that I didn't need to do anything different with the HK system.

Pros: Easy to install, works great. I'm not sure why people are having trouble installing this. You crimp or solder one end to the aftermarket BMW harness and the other end to your stereo harness. The wires are all labeled so it's not difficult to match them up. After everything is connected turn on the stereo and adjust the two pots until it sounds good without clipping. Then stuff everything into your dash. Easy.

Cons: The unit is fairly large, which makes fitting it behind the dash more complicated on cars with little space back there. For BMW E46 I found it much easier to stuff into the dash after I removed the entire bracket that houses the stereo and A/C controls. The A/C controls just pop right out which reveals two more screws to take out the whole bracket. Makes the stereo install a snap.


Written by: AJohnson from PNW, Washington on June 30, 2012

Crutchfield Customer Review (What's this?)

Works as advertised although the instructions have a lot of steps and wiring it in is not real clear...

Pros: Nice solution to keep steering wheel controls functional with aftermarket head units.

Cons: Dismal instructions and way too many steps to set up. Push this, hold this, then push that and then hold down this... Whew.

Unnecessary for e46 BMW

Written by: Drew from Saint Louis, MO on June 29, 2012

Crutchfield Customer Review (What's this?)

To be fair, it works as a LOC should; however, it is way too big and despite Crutchfields warnings was not needed for my install. I know this from experience because I tried the HU both with and without the LOC. With it, you could crank the stereo to 40, and it sounded like it was at 10. Without it, 40 shook the car, and no amps were blown in the process. Although it is true that a factory amp expecting a differentiated signal can be blown easier by a HU that does not have that output than one that does, it is also true that if you crank it way too high, you're going to blow something regardless. Be smart, take it easy on the amp, and the loc will not be necessary.

Pros: Decent gauge of copper wire used (Guessing around 14-16). Good instructions

Cons: Too big to fit in most places. Cover does not fit securely. Lowers signal from head unit far too much to be useful in an e46 bmw.

BMW install

Written by: PaulF from Chattanooga, TN on June 7, 2012

Crutchfield Customer Review (What's this?)

confusing unit at first, because of the car this is going in, installation has not been easy, four hours and the car won the first round, i plan on re-trying again this weekend and with luck will win round two!

Pros: Will let you know after complete install

Cons: as stated below the cover does not fit tight to the body so i will be using tape to secure as well, for the BMW E46 this was a problem to locate, had to run extra long wires to locate this in behind the glove box, calls to the manufacture on wiring was bad but the Crutchfield folks helped sort that out

Worked the first time

Written by: Jose E. from Chicago, IL on April 21, 2012

Crutchfield Customer Review (What's this?)

Installing a JVC head unit in my daughter's 2003 Santa Fe with a Monsoon system. I used the wired settings for input and and output and pretty much followed the included diagram. It was pretty straight forward. I made no adjustments and fired up the stereo and found the music to sound much better than it had with the old monsoon. No complaints.

Pros: Easy to install

Cons: Kind of cheaply made.

Don't Be Discouraged By Bad Reviews!

Written by: Wolflab1968 from Mammoth , WY on April 21, 2012

Crutchfield Customer Review (What's this?)

I was scared to death to buy this thing after Crutchfield told me I needed it, then after reading a bunch of horrible reviews. Everyone says it's a pain to wire. But if you ID ALL your wires ahead of time - speaker wires and others -- and don't do full solders right off the bat before testing it, you'll be fine. I had to call CF tech once because my Kenwood Excelon KDC-395's witing harness had an ignition, battery and ground that I wasn't sure where they connected to either the PAC or the 2003 OEM harness I was using. The first time I blew the 15amp audio fuse!! But in 2 minutes they fixed me up and it's all good. The only reason I notched it down a star is because it IS a little flimsy - the cover doesn't quite snap together tight. I just threw some elec tape around it. Adjusting wasn't an issue. Turn your HU up 3/4 and then adjust the pots on the PAC until it sounds sweet and rock on! No whine, no hiss. In fact, CF tech said most of the problems people reported are because they just don't have things hooked up correctly. There's a way to bypass factory amp, sure, but in the end you'll rewire more than the hour or two it took me to wire this up.

Pros: WORKS!

Cons: Flimsy, need some tech assistance figuring out perfect connection with OEM HU and OEM harness, depending on your system.


Written by: RickW from Lincoln, NE on April 14, 2012

Crutchfield Customer Review (What's this?)

They wiring diagram provided is useless, but a 5 minute phone call (free) to crutchfield will clear it all up! Everything worked great first try, no "noise" that other people talk about. Sounds great! Unit is quite large though, which I was able to fit behind my stock radio, but I'm sure other vehicles may not have enough space!

Pros: Everything!

Cons: Size

Garbage - try and find an OEM-1 kit or the OEM-2 instead!

Written by: RickNY from Long Island, NY on April 7, 2012

I used the unit in a 2010 Nissan Frontier Crew Cab that had the Rockford Fosgate premium system. I added a JVC head unit that only had 2.5V of pre-amp power. If you use the 70-7551 Metra adapter that Crutchfield provides on a system with 2.5V preamp output, you will be disappointed with the volume level of your new aftermarket head unit.

Using in this fashion, you use the high level speaker outputs of your new head unit and feed them into the input side of the SOEM-4.

Now. Here are the problems with this unit: - It is constructed like junk - The cover will pop off constantly unless you secure it with tie wraps on both sides - The audio quality is terrible once it reaches your amp. No amount of "tweaking" will leave you happy - There is a constant hiss that comes through once you have it hooked up - SIZE. This thing is HUGE. Combine that with the harnesses on both ends, and finding room will be a challenge

I pulled the unit out of my truck after a week. Instead, I hunted down one of PAC's previous products, the ROEM-NIS2, which incorporates the Nissan harness into the unit, and is constructed MUCH better. Most importantly, audio quality on the OEM-1 that comes in that kit is much much better. Size is also much better, and you end up dealing with many less wires.

If you have a Nissan, and are dealing with a 2.5V head unit, hunt down an ROEM-NIS2 instead of using the 70-7551 or 70-7550 harness. You won't be disappointed.

Pros: - None that I can think of. It will marginally get you setup with your new head unit.


Noisy piece of junk!

Written by: David K. from New Jersey on March 3, 2012

2007 Pontiac Vibe
Crutchfield Customer Review (What's this?)

This interface introduced a awful high pitched noise when I installed it. I followed all of Crutchfield tech supports suggestions with no reduction of the noise. I removed the PAC unit and bought the Scocshe LOC unit. The Scocshe unit was silent as a church mouse! Stay away from this unit!

Pros: Easy to install

Cons: Noisy, large

Integrated perfectly

Written by: FastEddie from G-town,KY on February 29, 2012

Crutchfield Customer Review (What's this?)

I purchased this because it was recommended to integrate an aftermarket head unit with my stock amplified Harman Kardon sound system in my wife's E46 BMW. I'm not sure what it does but, it worked perfectly for my application. Sound is very loud and crisp.

Pros: Great sound

Cons: Very big and hard to find a place for it.


Written by: Really a piece of junk from philadelphia, pa on February 23, 2012

i agree with many of the reviewers. poor build quality not even sure if I need it. but with it. the sound quality sucks and is not loud. thinking about ripping this unit out totally.



Bulky and useless

Written by: Turk from Tampa, FL on October 4, 2011

2003 BMW 3 Series
Crutchfield Customer Review (What's this?)

Installed at first and tested. Sound quality wasn't there. It would cut off constantly. I like cranking up but even at 50 it wasn't loud enough. Besides, it is very bulky and no where to fit unless you extend the wires and tuck it under dash. Still have it but didn't use it. My new radio sounds great without it.



PAC SOEM-4 Factory Integration Adapter

Written by: wayne from westwood nj on September 12, 2011

1989 BMW 325I
Crutchfield Customer Review (What's this?)

waste of time poor directions sent back



A waste of time.

Written by: Paul M from Lincoln, NE on September 5, 2011

2005 Hyundai Santa Fe
Crutchfield Customer Review (What's this?)

According to Crutchfield I needed this item when installing a high end head unit to work with the factory Monsoon amplifier in my Hyundai Santa Fe. Okay I tried it... it worked poorly, caused alternator whine in the stereo system, and made my high end system sound terrible. I pulled the darn thing out, and just spliced into the pre amp out puts instead. The sound WITHOUT this piece of junk is now extremely awesome. I would tell folks to avoid the PAC like the plague. You can find excellent stereo equipment here, but this one item is useless and a waste of your time to try and use.




Written by: Anonymous from Mass on June 22, 2011

1990 BMW 325I
Crutchfield Customer Review (What's this?)

Big, bulky, cheaply made, and very unnecessary. Do not bother with this adapter, waste of the extra money. Did not even use in re-wiring my 1990 325i with an Alpine CDE-121 head unit



Poor Quality and very LARGE

Written by: JW from Raleigh, NC on June 20, 2011

1999 Mercedes-Benz C-Class
Crutchfield Customer Review (What's this?)

First this item is quite large for what it does. The sound quality is not real good at high volume (distorted) but I never have to crank it up so this is not big for me. The worst thing is the components soldiered to the main board came loose or the board is micro-cracked and caused one side of the vehicle to go silent. I can wiggle these components to cause the connection to connect/disconnect. Pitiful! I used electrical tape to torque the board so the components are making a connection now. What a rig! It works unless I hit a pot hole then one side goes out again. It was not my wiring job...I checked this thoroughly. I think I'll just design my own converter. It can't really be worst :)



Works fine

Written by: Bigoof from Florida on June 10, 2011

2003 Hyundai Tiburon
Crutchfield Customer Review (What's this?)

I found out I needed this thing to install an aftermarket deck into a 2003 Hyundai Tiburon. I had to contact Crutchfield tech support a couple of times due to the wiring diagram not quite making sense with the deck wiring diagram but the staff and tech guys walked me right through it. This thing is basically an antenuator that changes the impedance of your speaker set-up so as not to burn out the built-in receiver's amp. You will need to adjust each channel's level and there is no chart or guide as to what to set them at. I just had to use my ears. Works fine though.



Works in '02 BMW 330Ci with H/K sound

Written by: Shawn from VA, USA on May 10, 2011

2002 BMW 3 Series
Crutchfield Customer Review (What's this?)

Installed in my son's car this weekend along with a JVC KDA-815 Receiver.
Difficult to wire the unit, but not PAC's fault. BMW does not give much room to fit
this unit behind the dash. I was able to put in above the radio and below the air
ducts/vents. Works as designed. New radio is a big improvement over the stock
Business CD unit we had. Our car has the Harman/Kardon "upgraded" sound
system. I guess speakers are our next project.



Totally useless

Written by: Skiddzx from San Francisco, CA on May 2, 2011

Crutchfield Customer Review (What's this?)

This product is supposed to cut the amplified signal from the receiver before it gets to the factory installed amp, which boosts the signal back up again. This can't be good. In audio electronics "less is more," fewer components means clearer tunes. Plus this thing is huge (where to put it in my 300zx?) and is obviously made of some very cheap parts. After three calls to tech support I gave up trying to get it to work properly and I'm going to have to re-install new speaker cables in the entire car. There must be a better way...



Wow this thing is big

Written by: Thomas from Baton Rouge, LA on March 31, 2011

Crutchfield Customer Review (What's this?)

Where exactly do I put this thing? By the time you get the Axxess and this so that you can use your aftermarket head-unit, you have NO ROOM for your headunit. It does work, if you have a little electronics knowledge. Electronics knowledge is helpful because the instructions that come with this product are subpar. Overall I'll just say that this is a really disappointing necessity for some vehicles.



Not Good Enough

Written by: Ken from East Bay, California on March 29, 2011

2003 BMW M3
Crutchfield Customer Review (What's this?)

This product is doing what its supossed to do, make my aftermarket deck work with my BMW OEM amp. The problem is that it can't handle the the power when I have the deck turned up. I could turn my music up louder with the factory deck. At first I had my deck turned to Vol# 48 (with loud feat. off) and it sounded great, besides a slight crackle in the speakers once in a while. Aftrer the second song, the whole system goes quiet, even the bazooka tube thats running off its own amp (so I know the prob is with the PAC SOEM-4). This PAC SOEM-4 is shutting off at high volume, then turning on in 5 seconds just to shut off again. I found my max level is 37, and no higher, and even at that level you get the crackling sound out the speakers and now my system is quieter than the OEM stock was. I have to scrap the PAC SOEM-4 and my OEM amps. If you wanna move up to a loud sound system, this set up is not for you. If your thinking of changing the factory deck, I recomend you change the factory amps as well.

If dont plan to add a subwoofer or upgrade your speakers, than this PAC SOEM-4 does the the job, but don't expect to wake up the neighbors.

My system is in a 2003 BMW M3 with Harman Kardon and no NAV.




Written by: Ware from Cleburne TX on March 22, 2011

2003 Hyundai Santa Fe
Crutchfield Customer Review (What's this?)

The specific installation instructions for my application were not with the product or Master Sheet. After a couple of calls to tech support, I still haven't eliminated the ensuing alternator noise. The engine has to be running in order to test. I installed this as a Christmas gift in a car that's usually 5 hours away, so it's not an easy matter to tinker.



it works...

Written by: John from Boston, MA on February 3, 2011

I checked many reviews before purchasing this prodauct and seen many mixed reviews,
some saying it is a must and others saying they did the whole installation without it. I
installed it anyway just in case I needed it and didn't realize it until after the rest of the
install was complete so it turned out to be worth the time in the long run by not having to
do the install twice. But by doing this i'm not totally sure if it was required as I had seen
in some reviews and by what I was told over the phone by the tech who was helping me
with the purchase...



Good idea but could use improvement

Written by: DocGrubs from Boston MA on January 28, 2011

Crutchfield Customer Review (What's this?)

I installed this as part of an upgrade of my daughter's in-dash stereo in a 2006
Acura RSX Type S. I'm pretty handy and experienced with mechanical and
electrical repairs so not one normally to be befuddled by installation
instructions. The instructions were hard to figure out, I had to call
Crutchfield to verify which wires hooked up to the new and old wiring, and the
device was large and ungainly to place down in the back of the console. In the
end it all worked out fine but I can only imagine what it would have been like
for a newbie to install. If the unit were more compact and the wiring
instructions were clearer it would have been a dream.



Works perfect, just not the best construction quality

Written by: John from Reno, NV on January 26, 2011

2005 Mazda 6
Crutchfield Customer Review (What's this?)

This device took care of all my problems with tying into an existing Bose system. I took my
chances since it wasn't recommended for my vehicle - but voltage change is voltage change.

I haven't seen anything like it by any other manufacturer - so not much of a choice. The cables
are quality and design is nice. The only complaint I have is that the two halves pop apart rather
easily, on their own without any prying. I didn't worry about it too much and installed it anyhow
since it sets under the dash with no real chance of falling apart.




I don't know

Written by: Chuck from Central Florida on October 17, 2010

1994 Ford Aerostar
Crutchfield Customer Review (What's this?)

Well I installed it per instructions and didn't get any sound from speakers even with the pots turned all the way up. I removed it and installed my new Clarion cz100 without it and it worked perfect.
So I really can't recommend this product to anyone because it did not work for my in my install. I am going to give it to a friend and see if he has any luck with it.




Written by: Joe from Long Island, NY on October 5, 2010

Crutchfield Customer Review (What's this?)

For what it does there are passive designs (not needing 12v) It's large size would not have fit well in my dashboard, but that didn't matter because it didn't work anyway to let me use my JBL factory amp with an aftermarket HU. Crutchfield sent me this but I only needed a smaller one like OEM-2 which doesn't need to be powered and it worked fine. Also the directions were lacking in info regarding my situation.



PAC SOEM-4 Factory Integration Adapter

Written by: Gregg from Apopka, Florida on September 30, 2010

1984 Nissan 300ZX
Crutchfield Customer Review (What's this?)

Didn't work right- very low sound output. System works much better without it.



Good Bandaid

Written by: Anonymous from Huntsville, Al on September 29, 2010

2006 Acura RSX
Crutchfield Customer Review (What's this?)

If you have a bose system this will allow you to step down the voltage (volume)
so you can turn your Cd player up past 10.



PAC SOEM-4 Factory Integration Adapter

Written by: Mark from bethesda maryland on August 25, 2010

2005 Nissan 350Z
Crutchfield Customer Review (What's this?)

The adapter is sliding around in the trunk of my car. The installer said it was completely unnecessary. That htye were able to plug the JVC radio into the wiring harness directly. I doubt I'll get around to sending it back. I'll probably just pitch it in the trash



PAC SOEM-4 Factory Integration Adapter

Written by: Derek from Atlanta, GA on June 27, 2010

2003 Acura 3.2CL
Crutchfield Customer Review (What's this?)

Easy to follow instructions. No hum, popping, whirring, or anything to detract from the sound.



OK? I Guess.

Written by: Zac from Oklahoma on June 13, 2010

2005 Nissan Maxima
Crutchfield Customer Review (What's this?)

I was told by Crutchfield I needed this. Just took their word for it. Really have no idea what it does (I'm basically using it as a passthrough).

Only thing I can figure is that since Bose speakers have integrated amps and only need 1ohm signal, and receivers are 4ohm usually, that this thing solves that issue. Other than that I don't know. Seems to work fine!



Hands-on research

What's in the box?

Download owner's manual

  • 4-Channel line output converter
  • Two speaker-level harnesses (one attached)
  • Low-level RCA harness (attached)
  • 4 Mounting screws
  • General Wiring Instructions

Product Research


Overview: The PAC 4CH Programmable Source Unit Interface (SOEM-4) is a 4-channel premium line-output converter with a remote turn-on trigger. The PAC SOEM-4 is a one-device solution for today's OEM/Aftermarket vehicle sound systems. It features programmable input and output circuitry with slide switches, which allows connection of RCA level or speaker level input and output. DC coupling circuit ensures noise free integration and no load induced on the factory system (this is in contrast to a normal LOC which uses resistors and can stress a factory radio's circuitry).

Optimal Sound Performance: The PAC SOEM-4 is transformer isolated for optimal sound and performance. The SOEM-4 maintains correct phasing and is capable of supporting a 20 to 20,000Hz audio signal.

Switchable Input/Output Signal: The PAC SOEM-4 includes one low-level RCA harness and two high-level speaker harnesses. The included harnesses along with the top-mounted Input/Output switches allow you to select the type of input and output signal going in and out of the SOEM-4 interface. You can choose either low-level (RCA) or high-level (speaker wire). 

Note: 4-volt minimum RCA level, if using RCA signal as input.

Remote Turn-on Trigger: The PAC SOEM-4 provides 12v amplifier turn-on trigger wire. The SOEM-4 utilizes signal sense to detect when audio is present in the device, and creates a 12V output usable for triggering an external aftermarket amplifier.

Output Level Adjustment: The PAC SOEM-4 line-output converter is equipped with output level controls that can be adjusted for proper sound level matching, for each channel (LF, RF, LR, and RR). This is done by inserting a small flat-blade screwdriver into the gain adjustment holes, located on top of the SOEM-4. By turning clockwise, the gain for that individual channel, or the amount of sound allowed to pass through the SOEM-4 is increased. By turning counterclockwise, the gain for that individual channels is decreased.

Rear Installation:The PAC SOEM-4 can be connected in the rear of the vehicle for convenient amplifier installation. When this item is used as a factory amp interface, it locates behind the new radio.

Mounting: The SOEM-4 line-output converter features integrated mounting flanges and comes supplied with four mounting screws to mount the interface in your vehicle.


  • Low Level Harness:
    • 12V Power (yellow)
    • Ground (blue/black)
    • Remote turn-on (blue)
    • RCA LF (left front)
    • RCA RF (right front)
    • RCA LR (left rear)
    • RCA RR (rear rear)
  • Speaker Level Harness
    • LF+ (white)
    • LF- (white/black)
    • RF+ (gray)
    • RF- (gray/black)
    • Ground (black)
    • LR+ (green)
    • LR- (green/black)
    • RR+ (purple)
    • RR- (purple/black)

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.