1.888.955.6000
 
 
1-888-955-6000
crutchfield.com
Crutchfield

NAD DAC 1

Wireless USB digital-to-analog converter

Zoom
  • NAD DAC 1

    Front

  • NAD DAC 1

    Rear panel line drawing

  • NAD DAC 1

    Shown with USB transmitter connected to laptop computer

 

Our take on the NAD DAC 1

by Dave Bar
NAD

Turn your computer into a hi-fi component — wirelessly

Wouldn't it be great if there was an easy way to take all of the music that you enjoy on your computer — from CDs and MP3s to streaming Internet radio — and send it to your trusty, big-rig stereo? And have it sound fantastic? Now there is. NAD's DAC 1 wireless digital-to-analog converter offers a simple solution that turns your computer into a high-quality audio source. Anything that you can listen to on your PC or Mac® can be digitally transmitted to your existing home theater or stereo. This two-piece DAC features point-to-point wireless technology that delivers uncompressed, full-bandwidth audio from your desktop or laptop to your home system to give you the best possible sound quality. And because it's a closed wireless system, you don't even need a Wi-Fi® network to use it.


transmitter_connected_to_PC

The DAC 1's two-piece wireless design makes it easy to enjoy computer-based music on your home audio system.

Simple to set up. Easy to use.

Right from the box, the DAC 1 is ready to play in just moments. Simply plug the included transmitter module into a USB port on your computer, and the DAC 1 essentially becomes your PC's sound card. The transmitter bypasses all of the analog circuitry in your PC and transmits a digital signal directly to the receiver module that's connected to your hi-fi system. The digital signal then gets converted and sent as an analog signal to your stereo amplifier. The DAC 1 uses premium digital and carefully selected passive components in a proprietary circuit for incredibly musical sound. It also sports a coaxial digital output that allows downstream digital processing by a different DAC or home theater receiver.


Highlights:

  • Burr-Brown TI PCM1781 digital-to-analog converter
  • wireless USB transmitter dongle plugs into your computer
  • Wi-Fi network not required — uses point-to-point 2.4GHz wireless technology for uncompressed, full-audio-bandwidth transmission
  • built-in driver for USB connection
  • stereo RCA and coaxial digital outputs for connection to a stereo or home theater system
  • transmission range: up to 131 feet
  • supports audio sample rates up to 48kHz/16-bit
  • frequency response: 20Hz to 24kHz (± 0.5 dB)
  • THD + Noise: 0.05%
  • signal-to-noise ratio): greater than 80 dB
  • external power supply with 58" cord included for DAC receiver
  • 7" mini-USB (type-B) to USB (type-A) adapter cable for USB transmitter included
  • 50" stereo audio RCA cable included
  • 5-1/2"W x 2"H x 3-13/16"D (DAC receiver)
  • 1-1/2"W x 5/8"H x 3-1/4"D (wireless transmitter)
  • warranty: 1 year
  • Our 60-day money-back guarantee
 

Hands-on research from the Crutchfield Labs (what are the Labs?)

Product Research
What's in the box?

Download owner's manual

  • Wireless USB DAC receiver
  • Wireless USB DAC transmitter
  • AC power supply (with attached 58" DC cord)
  • 7" mini-USB (type-B) to USB (type-A) adapter cable
  • 50" Stereo audio RCA cable
  • Federal Communication Commission Interference Statement

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 open the box, verify contents, 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.

Features
Specifications
Dimensions

Features

Overview: The NAD DAC 1 Wireless USB Digital-to-Analog Converter lets you wirelessly stream music from your computer (PC/Mac) to your Hi-Fi stereo system with high performance sound. The NAD DAC 1 uses point-to-point 2.4GHz wireless technology which means you can just plug in the two-piece DAC 1 and start enjoying computer audio from your home entertainment system in minutes.

2.4GHz Wireless Connection: You don't need a Wi-Fi network to connect the NAD DAC 1 to your computer and home audio system. The NAD DAC 1 Wireless USB Digital-to-Analog Converter uses point-to-point 2.4GHz wireless technology which features the full audio bandwidth (20-20kHz) and remains uncompressed to maintain sound quality.

Simple Installation: The NAD DAC 1 Wireless USB Digital-to-Analog Converter consists of a wireless Receiver and Transmitter. Simply plug the DAC 1's Transmitter into your computer's USB port and it becomes a sound card that transmits your computer's audio wirelessly to the DAC 1's Receiver, which connects to your home receiver via a stereo analog or coaxial digital connection.

Note: There are Channel switches (1-3) on the Receiver and Transmitter. Make sure these switches are set to the same number.

Wireless USB DAC Transmitter: The DAC 1's Transmitter consists of a mini-USB (type-B) connector with a mini-USB (type-B) to USB (type-A) adapter cable. Using the included USB cable, the DAC 1's Transmitter plugs into your computer's USB (type-A) port and bypasses all the analog circuitry in your PC and then wirelessly transmits audio directly to the DAC 1's Receiver, which is connected to your hi-fi system, using the native digital format for the best possible sound.

Wireless USB DAC Receiver: The DAC 1's Receiver consists of a integrated Digital-to-Analog Converter with analog & digital audio outputs. Once the wireless audio is received at the DAC 1's Receiver from the DAC 1's Transmitter, the digital signal is converted and sent as an analog signal to your home receiver through stereo analog audio outputs. There is also a coax digital output that allows downstream digital processing.

24-Bit/192kHz DAC: To achieve the best possible sound, the DAC 1's Transmitter digitally transmits the audio from your Mac or PC to the DAC 1's Receiver, which then converts the digital signal to analog using premium Burr-Brown OPAmps (TI PCM1781) and 24-bit/192kHz DACs with selected passive components in a proprietary circuit.

Compatible Sampling Rates: The NAD DAC 1 Wireless USB Digital-to-Analog Converter supports audio sampling rates up to 48kHz/24-bit.

Audio Outputs: The NAD DAC 1 Wireless USB Digital-to-Analog Converter is fitted with both analog & digital audio outputs

  • Analog Output: The NAD DAC 1 features one stereo audio RCA output to connect to your home stereo receiver.
  • Digital Output: The NAD DAC 1 features one coaxial digital output to connect to your home theater receiver.

AC Power Supply: The NAD DAC 1 Wireless USB Digital-to-Analog Converter includes an external AC power adapter.

Specifications

Sample Rate: 48kHz/16-bit

THD+N: 0.05% (ref 0dBFS)

Signal-to-Noise: > 80dB

Analog Output Level: 2V

Coax SPDIF: 500mV +/- 50mV

Frequency Response: 20Hz to 24,000Hz (+/- 0.5dB)

Time Delay: <18ms

RF Band: 2.4GHz

Transmission Range: 131' (40m)

Dimensions

DAC Receiver:

  • W = 5.5"
  • H = 2.0"
  • D = 3.8125"

Wireless Transmitter:

  • W = 1.5"
  • H = 0.625"
  • D = 3.25"
 
Review this product
Great Gear Giveaway rewards card

Submit a review and you will be entered to win a $150 gift card

Crutchfield Great Gear Giveaway Official Sweepstakes Rules

NAD DAC 1 Reviews

Average Customer Review:

16 people say:

Review this product:

Thanks for taking the time to share your experiences about this product. Please be sure to focus your comments on the product itself. Read our Review Guidelines for more information.

Your email won't be visible. Please use the email address that is associated with your order.
(e.g., JohnD) Your review will be signed using the display name and location
(e.g., Charlottesville, VA)

Click on a star to rate the overall product on a scale of 1-5
1500 characters left
Attach a YouTube Review
Crutchfield Video Review Guidelines
  • Only submit videos that you made or are authorized to use.
  • Do not submit videos that contain music, video or visuals that are copyrighted and belong to someone else.
  • Please see our Review Guidelines for more information.
500 characters left
500 characters left
Filter by rating:
5 out of 5

GREAT little gizmo

Written By Jeff H, Cambridge, NY on Saturday, March 15, 2014
Crutchfield Customer Review (What's this?)
 
This NAD wireless DAC does everything it claims to- streaming CD quality sound directly from your computer to your home audio system without a glitch. I was a bit skeptical at first, expecting a somewhat compromised sound from such a diminutive and inexpensive unit, but man was I surprised. What I heard was just a few millimeters off from the CD and if I hadn't done an A/B test, I might not have been aware of the difference. Unless you have a significant number of high def audio files stored on your machine, this is ALL you need. If you are a high def connoisseur, the NAD wireless DAC 2 will no doubt do the trick for you. Highly recommended- I now have 2 of them, one going to the living room and another to my high end system.
Pros:
Easy to use, bullet proof, clean pristine sound, inexpensive
Cons:
Doesn't stream high def files- limited to 44k, 16 bit audio (CD quality)
Was this review helpful?    Yes | No
 
5 out of 5

Really Happy

Written By Gary L., Napa on Thursday, February 13, 2014
Crutchfield Customer Review (What's this?)
 
After reading through the various reviews I was concerned about how easy to use or effective the DAC 1 would be. As it was bundled with my new NAD Integrated Amplifier I wasn't to concerned if it didn't perform to the standards I expect from NAD. I was already contemplating a future purchase of the NAD C 446 Digital Media Tuner, but it's totally not necessary now. With the DAC 1 everything from my computer/internet is now being played with great clarity through my NAD Amplifer, without any interruptions or interference to my Wi-Fi.
Pros:
Easy to setup. Seamless transmission to my amplifier.
Cons:
None that I've encountered.
2 out of 2 people found this helpful
Was this review helpful?    Yes | No
 
2 out of 5

NAD DAC 1

Written By Terry, NY, NY on Saturday, February 01, 2014
Crutchfield Customer Review (What's this?)
 
I tried it with 2 different WIFI networks in different locations, plugged into same type of Dell 660 desktop with the same network card DW-1056. In one case it worked w/o any problems in another it consistently killed WiFi connection in 5 seconds. NAD adviced me to get longer USB cable. I tested 3 ft cable and the WIFI connection held. However, the music would sometimes pause for several seconds. Also sometimes there was scratching sound from the speakers while music was playing. I could hear this when streaming Pandora, paying CD in PC and playing MP3 file. So it looks like the problem is in DAC itself. Crutchfield gives away this DAC for free when you buy NAD integrated amp. However I spend several hours trying to make it work, etc.

If you have WIFI, I would stay away from this.
Pros:
Great when works but unreliable
Cons:
Kills 2.4Ghz WIFI. Unreliable
Was this review helpful?    Yes | No
 
3 out of 5

The jury is still out...

Written By Coastie, Atlanta, GA on Tuesday, July 30, 2013
Crutchfield Customer Review (What's this?)
 
This product does what it is intended to do, but, it doesn't do it consistently. I'm not saying it doesn't work, just not reliably. I love the idea of streaming from the computer, but I think the technology may not quite be there yet... Since beginning to use it, I've noticed that I've had to occasionally reload the webpage, and our wi-fi has become intermittent. These weren't issues prior to using the NAD DAC...I've tried to select different channels (there are 3 of them) to see if it made a difference, but no luck. I'm not sure if I will keep or return the product, though I'm planning to discuss with Crutchfield to resolve the issues before returning.

Crutchfield is awesome - I've been their customer for over 20 years and appreciate their expertise, patience, and customer service.
Pros:
It works - kind of...
Cons:
seems to affect wi fi signals
2 out of 2 people found this helpful
Was this review helpful?    Yes | No
 
4 out of 5

Serves it's purpose well but nothing great!

Written By jinxeddeep, Dearborn, MI on Wednesday, May 01, 2013
Crutchfield Customer Review (What's this?)
 
This device, for someone like me who likes to explore different kinds of music and artists, is a must. There is no discernible lag from laptop/desktop to my hi-fi system. If you have interference issues, you can switch between the different channels this devices operates on. I feel that for their original MSRP they could have used 5 GHz band instead of the universally used 2.4 GHz band. The MSRP for this device is ridiculous. No wonder they decided to drop the price. The Audioengine W3, its main competitor, costs less and there is really no added benefit to the extra money you put down for this one. I also don't like the fact that they advertise it as having a 24/192 DAC, which truthfully it does, but is useless since the transmission is only done at a maximum of 16/44.1. The 24/192 DAC in the receiver is neither an upsampling DAC nor can it be used with sources other than the transmitter for one to take advantage of it (there are no digital ins). The only difference between the W3 and this device is the optical out on the receiver that lets you use and external DAC. Otherwise, the transmission itself works smoothky most of the time and the unit is well built.
Pros:
Build Quality Low interference/ability to switch channels
Cons:
Price
8 out of 8 people found this helpful
Was this review helpful?    Yes | No
 
5 out of 5

great nad dac 1

Written By spw, nyc on Thursday, March 07, 2013
Crutchfield Customer Review (What's this?)
 
Terrific DAC-Simple to connect-the music is very clear and sharp-Very impressed.
1 out of 3 people found this helpful
Was this review helpful?    Yes | No
 
2 out of 5

If only it didn't drop out

Written By Jim B, Atlanta on Tuesday, January 15, 2013
Crutchfield Customer Review (What's this?)
 
I read the reviews about the issue of wifi signal interference, dropouts, etc. But I thought it had to be an isolated issue. My NAD amp is so... SO awesome... there's no way this product would let me down. But it does. When the dongle is plugged in, it slows down my Internet connection to the point I can't really do much. And it cuts out frequently enough it's a problem. I submitted a trouble ticket to NAD and even spoke with one of their tech people. He said this isn't a prevalent issue--that he's only had two calls on it. Strange, because every online review I see mentions it.

When it's not dropping out, the sound is pretty decent. A few complex passages tripped it up, but overall, I would say it's excellent in the sound category. Too bad its other issues are insurmountable. This one's going back. NAD, you let me down on this one.
Pros:
Great sounds, easy to use
Cons:
Wifi sends it all crazy, dropouts
6 out of 6 people found this helpful
Was this review helpful?    Yes | No
 
4 out of 5

NAD DAC 1

Written By g_w_st_george, St. George, UT on Monday, December 24, 2012
Crutchfield Customer Review (What's this?)
 
The sound is wonderful. We have enjoyed listening to streaming audio from the Internet and played over our ... NAD ... stereo system. The problems began shortly after installation, however. My Internet connection banged out unceremoniously. Yes, I read the reviews and knew that could be a problem. But, I have wireless N and a wireless N router, right? Should be on 5GHz, no problem. No, it's on the 2.4GHz band and it is a major problem. The short USB cable didn't get the transmitter anywhere far enough from my iMac's wireless radio transmitter ... Bang. Dead.

Through a great deal of trial, like selecting each of the 3 positions on the NAD transmitter, then going through an Internet speedtest, I found that position 3 on the transmitter box and channel 10 would provide the best Internet throughput and the least disruption of the wireless network to that computer. The hassle of installation is now a smaller problem, but realistically NAD should choose a different wavelength to transmit on rather than the most common wavelength of wireless networks!
Pros:
Sound quality is excellent. Very few drops in streaming, once you establish a good connection that won't bang out the wireless network. I was able to find a longer USB cable in my junk box. Getting the transmitter several feet away from the computer helped stabilize the wireless network most of the time.
Cons:
The wireless network issues can be frustrating. When I called Crutchfield tech support, the answer that I received was, "Bummer. You bought a product that transmits on the same frequency as your wireless network. Sorry about that." I'm quite certain that I'm not the first person to have this problem, and some things that worked for other folks might have been helpful.
5 out of 5 people found this helpful
Was this review helpful?    Yes | No
 
5 out of 5

Works wonderfully

Written By George, Atlanta, on Thursday, June 14, 2012
Crutchfield Customer Review (What's this?)
 
wonderful product. Excellent sound. First one didn't work for some reason, red lights all the time. Crutch field tech and service process easy. Returned and received replacement that works flawlessly. Love this product and appreciate Crutchfield service.
Pros:
excellent streaming audio sound
Cons:
USB cord shouldn't be necessary. Should plug in directly
1 out of 1 people found this helpful
Was this review helpful?    Yes | No
 
5 out of 5

WOW! DOUBLE WOW!

Written By DeeZer, San Jose, CA on Monday, June 04, 2012
Crutchfield Customer Review (What's this?)
 
I purchased the NAD DAC-1 based solely upon the Crutchfield reviews I read. For many-many years, I have used a complete computer system as a jukebox to play my ever-growing MP3 collection. A typical setup would include an old Macintosh computer complete with monitor, keyboard and mouse. The fun was figuring out how to locate the aforementioned hardware with one of my four NAD integrated amplifiers without creating a monstrous array of equipment. By-the-way, I love NAD equipment!

Setup is quite easy, as long as you remember to go to the sound control panel on your computer, and set the output to head phones. A blue light on both parts of the NAD provided equipment means you have a ready network. Don't worry about the need for inline sight. It's not necessary. The quality of sound is excellent.

My only suggestion for improvement would be a lower cost second receiver to be placed with a second sound system, or a third sound system, or as is the case in my life - a fourth sound system.
Pros:
Quality sound distribution without the need for hard wiring to the amplifier.
Cons:
None worth mentioning.
Was this review helpful?    Yes | No
 
1 out of 5

no distance

Written By bjack, new york on Monday, May 21, 2012
Crutchfield Customer Review (What's this?)
 
Works well, but only when few feet away. You have to be close enough that it would almost be easier to plug in a wire. My cordless phone and airport extreme are located in the same room as my stereo, both reach my computer (one room over), but the nad does not. Im too lazy to return, but I should; it does not even come close to doing what I needed it to do. However, when close enough, it sounds good.; hence one star.
3 out of 5 people found this helpful
Was this review helpful?    Yes | No
 
5 out of 5

Great Product! Can't find a mistake with NAD yet, lol!

Written By M. D, New York City, NY on Tuesday, May 15, 2012
Crutchfield Customer Review (What's this?)
 
Don't know why it didn't work well for some of the people on this review but it works very well for me. Get the right RCA cables such as Audioquest G-snake and u should be happy. The sound quality is so good that I'm mad that i didn't know about this product. Will blame it on Crutchfield lol, only kidding. If you have a computer and already have a home theatre system, u don't need speakers for your computer; get these and you're all good.
Pros:
Ease and sound quality.
Cons:
NONE.
2 out of 3 people found this helpful
Was this review helpful?    Yes | No
 
2 out of 5

works....most of the time

Written By Michael, Boulder, CO on Tuesday, April 10, 2012
Crutchfield Customer Review (What's this?)
 
This item works as advertised but occasionally knocks out the internet connection. The browser will freeze up and if you're streaming audio that will stop as it tries to rebuffer. If you unplug the usb cable for this unit the connection quickly re-establishes but if you leave it plugged in you will get a internet connectivity error message. Called Crutchfield for an RMA label. 8 minutes on hold with annoyinglly loud recorded messages and poor quality hold music. Service rep wanted me to troubleshot with support - no thanks, this item should work fine as my computer was & is working great with out it. I'll wait for the next generation model.
Pros:
Small. The Burr Berry DAC improves sound quality.
Cons:
Expensive, occasionally knocks out internet connection
5 out of 9 people found this helpful
Was this review helpful?    Yes | No
 
5 out of 5

Works!

Written By Oleander, Danville, VA on Monday, March 05, 2012
Crutchfield Customer Review (What's this?)
 
This device works exactly as advertised. It allows me to transmit streaming radio from my computer to one of my stereo outfits in another room, and listen to MP3 and Wave files on a stereo system that doesn't have a USB port. Now, some reviews complained that the sound was a bit thin. I found that the sound out of the box was quite satisfactory, but it really opened up when I added a little Chinese tube buffer between the DAC receiver and the pre-amp. You might try that! Anyway, while hard-core audiophiles will probably be more satisfied with a vastly more expensive unit, this serves my purposes admirably. A steal for the price! And, of course, NO ONE has better customer service than Crutchfield.
Pros:
Easy to set up, silent, musical, effective.
Cons:
Slightly inconvenient to have to switch between sound cards (the DAC and an M-Audio internal) to redirect the sound from the computer speakers to the stereo in another room (facilitated with a desktop shortcut), and it causes a slight buzz at times with a cordless phone (I just unplug the transmitter during phone calls). Nothing serious!
Was this review helpful?    Yes | No
 
3 out of 5

I'm sticking with wires.

Written By JonnyE, Atlanta, GA on Thursday, February 16, 2012
Crutchfield Customer Review (What's this?)
 
I was satisfied with the sound quality. The product works as advertised, and the wireless transmission did not introduce any static or noise. However, I ended up returning the product because I found that it slowed down my internet browser. The problem was sporadic, but occurred often enough to concern me. The problem occurred even at times when I was not playing music or producing any sound output. The browser would jam up, and then start working again when I unplugged the NAD DAC1.
Pros:
Convenient, good sound.
Cons:
Slows down browser.
4 out of 4 people found this helpful
Was this review helpful?    Yes | No
 
4 out of 5

Plug and play, sounds good

Written By abd4evr, Central PA on Monday, December 12, 2011
Crutchfield Customer Review (What's this?)
 
Was a little skeptical about it at first. Product comes in a box with a simple diagram of how to use it on the box, but no documentation inside. Was instantly recognized by my PC as "USB headphones," but was not clear how to get it to work with my J. River Media Center v. 17 with anything other than Direct Sound or WAV out (which limits sound quality). After some digging, tried ASIO4ALL (free software), which recognizes the "USB headphones," and will play to them. With it set up that way, sounds pretty good playing WAVs from my computer. Sends signal from my computer about 40 feet to a utility closet where my amp is, going through several plaster walls, a brick wall and a wall with a fridge and oven in it. I was worried about interference from my router/WAP and cordless phones, all in the same room as the NAD emitter, but no problems so far.
Pros:
Very simple, sounds good, pretty good range.
Cons:
Poor, well no, documentation, no online support at NAD, have to research to find out how to use ASIO for it.
8 out of 9 people found this helpful
Was this review helpful?    Yes | No
 

Add accessories for the NAD DAC 1

Top-notch analog audio cables help deliver premium sound quality from your DAC to your amp or receiver. See all categories & accessories

AudioQuest Evergreen Stereo interconnect cable with RCA plugs (0.6 meter/2 feet)
30 people say
Your Price: $31.99
Add to Cart
Monster Cable Stereo Audio 400i Stereo interconnect cables with RCA plugs (1 meter/3.3 ft.)
4 people say
Your Price: $39.95
Add to Cart
AudioQuest Golden Gate Stereo interconnect cable with RCA plugs (0.6 meter/2 feet)
15 people say
Your Price: $64.99
Add to Cart
AudioQuest Big Sur Stereo interconnect cable with RCA plugs (0.6 meter/2 feet)
2 people say
Your Price: $96.99
Add to Cart
AudioQuest Sydney Stereo interconnect cable with RCA plugs (0.6 meter/2 feet)
4 people say
Your Price: $154.99
Add to Cart
Monster Cable® Digital Life™ High-Speed Mini 1.5-ft. USB cable (Type A to Mini Type B)
Your Price: $19.95
Add to Cart
Monster Cable® Digital Life™ High Speed USB cable (Type A to mini Type B) (3 ft.)
1 person says
Your Price: $24.95
Add to Cart
AudioQuest VDM-A Coaxial digital audio cable (3 meters/9.9 ft.)
6 people say
Your Price: $29.99
Add to Cart
AudioQuest VDM-X Coaxial digital audio cable (3 meters/9.9 ft.)
2 people say
Your Price: $54.99
Add to Cart
AudioQuest VDM-1 Coaxial digital audio cable (2-meter/6.6 feet)
1 person says
Your Price: $54.99

After $30.00 Special Purchase

Add to Cart
Arista 18-5460 6-foot coaxial digital audio cable
3 people say
Your Price: $10.99
Add to Cart
Panamax M8-AV Power line conditioner and surge protector
7 people say
Your Price: $119.99
Add to Cart
Panamax PM8-AV Power line conditioner and surge protector
3 people say
Your Price: $89.99
Add to Cart

Why choose SquareTrade?

The #1-Rated Protection Plan

Thousands of people have reviewed SquareTrade Protection Plans — and made us #1.

5-Day Service Guarantee & Free Shipping

We'll repair or replace your item in five business days or less after we've received it, or your plan is free. And, as always, we pay for all shipping.

Protection from Normal, Everyday Use

Repairing your average mechanical or electrical failure can cost as much as buying a new device. With SquareTrade, you're covered — including parts and labor.

For a more in-depth review and enhanced detailed information on the NAD DAC 1, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_745DAC1/NAD-DAC-1.html ).

Get live, personalized service from an expert

Crutchfield Advisor: Hi there.

Crutchfield Advisor: We're happy to answer questions or provide additional info about this item.

Advisors also available at 1-888-600-3963

Searches related to the NAD DAC 1 Wireless USB digital-to-analog converter