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PA amplifiers buying guide

How to choose a professional-grade power amplifier for your PA system

In this article: Trying to figure out how to choose between the different models of PA power amplifiers? We'll talk about some basics, then cover what to look for, including...

How many channels do you need?

How much power do you need?

What you need to know about the connections

...along with explanations of the onboard features you'll find on pro audio power amplifiers that'll help you set up and fine tune your system.

You'll find PA power amplifiers at the heart of pretty much any serious professional live sound system. Their job is simple: to amplify incoming sound signals from your mixer and drive them through passive PA loudspeakers.

PA amplifiers are designed to withstand the rigors of live performance situations. That means they can handle a certain degree of unintended abuse. Most models have robust protection circuits, trouble-sensing signal limiters, and other safeguards. When pushed too hard, they protect themselves, save your speakers, and prevent audible distortion.

PA amps installed at a bar.

We recommended two Crown amps for a local nightclub's PA system.

Pro amps are versatile, too. That means they can safely adapt to a variety of speaker system configurations. Models with digital signal processing (DSP) let you tailor the amp’s output to suit your speakers and the space they’re in.

How many amps (or amp channels) do you need?

Most PA amplifiers have two channels. You'll find four- and eight-channel amps, mostly in permanent-installation sound systems or large-scale touring PAs. In any case, each channel corresponds to a single set of speaker connections.

Say you want to power your two main, audience-facing speakers, one on each side of a stage. A single two-channel amp is a great choice.

You might want a second two-channel amp to power two monitor speakers. Monitors are the wedge-shaped speakers that sit on the stage floor and fire sound up toward the performers so they can hear themselves.

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A two-channel amp and a pair of passive speakers work well in a small space. For a medium-to-large venue, it might make sense to add additional stereo amplifiers to power your monitors, speakers, and subs individually.

If you need a lot of bass, your system should include one or more subwoofers. You can use a two-channel amp in “bridged” (one-channel) mode to power a subwoofer. Bridged mode combines the power of both channels, sending more power to a single output.

Amplifier bridged mode hookup detail on back of amp

Bridging two channels gives you their combined wattage — useful for a power-hungry speaker like a subwoofer.

For more information about system configurations, read our intro to live sound equipment.

How much power do you need?

Remember: PA amplifiers and passive PA speakers depend on each other to sound their best. That's why the truest answer might be that your amp needs to have as much power as your speakers can handle.

PA speakers typically have three power ratings that you want to understand: "continuous" (or "noise"), "program," and "peak."

The continuous/noise rating is the minimum power required to power a speaker in real-world situations. Peak power is the maximum the speaker can handle in short bursts. It's kind of like your car. The speedometer might show you that you can get up to 120 miles per hour, and you probably can. But if you drive 120 mph for an extended length of time, you'll burn up your engine.

Program power is twice the continuous/noise rating. And program power is what you want to look at when you're choosing an amp to match speakers. If you underpower your speakers, you'll have to crank up the amp's volume, which can cause unpleasant distortion.

Your speakers' manual will give you their peak and program power ratings, and most likely even a recommended amplifier power range.

illustration of too little or too much amplifier power

Having the right amplifier power is important for clear sound and the welfare of your speakers.

Amplifier power and speaker impedance

You’ll get the best performance if your speakers' total ohm load — or impedance — matches that of your amplifier.

An ohm is a measure of electrical resistance. But what is "resistance"? Think of the power an amp delivers to a speaker sort of like water flowing through a hose with an adjustable spray nozzle.

You can screw the nozzle down so far — increase the resistance — that you choke the water off completely. Or you can take the nozzle off and remove all resistance — plenty of water, but splattering on the ground instead of in a focused stream.

If the total impedance — or ohm rating — of your speakers is too high, your amp can’t deliver enough power. If it’s too low, then the amp could over-deliver, overloading your speakers and possibly damaging the amplifier.

Impedance matching formula

Most PA amplifiers are designed to work with four- or eight-ohm speaker loads. Check your amplifier and speaker manuals to figure out their impedance rating.

You can connect any number of speakers to one amplifier, as long as their total resistance doesn’t fall below the amp’s impedance.

The different ways you can wire speakers can get pretty techy. But in almost every case, you'll be connecting PA speakers to an amplifier in what's called a parallel configuration.

You use a simple — if not completely intuitive — formula to calculate the total resistance of your speakers, depending on whether you connect one, two, or more to a single channel

You’ll get the best results when you use cabinets with the same ohm rating. Then to calculate the total ohm load, you divide that ohm rating by the number of cabinets you’re connecting.

Diagram of parallel speaker wiring

When you wire two eight-ohm speakers in parallel, they present a total load of four ohms to your amplifier.

Getting the most out of your PA amplifier

The amount of power an amplifier can deliver depends on the impedance (or resistance) of the speakers it's driving. So you might see an amp that puts out 1,000 watts into eight ohms and 1,500 watts into four ohms.

Keep this in mind when you’re shopping for speakers. Most PA speakers are eight ohms. Choose four-ohm speakers like the JBL PRX425, and you’ll get more power out of your amp.

Amp classes

When shopping for PA amps, you may notice that they come in different "classes." The class designations tell you something about the design of their output stages. Check out our article on amp classes to learn more.

Most of the PA amps we offer are Class D. This is the most efficient class of amplifier. Class D amps are much lighter and run cooler than other types.

We also offer a few Class AB amps. They are heavier than Class D amps and run noticeably warmer. Watt-for-watt, you are unlikely to hear the difference between the classes, especially in a live sound situation.


“Headroom” is a term that sound pros use a lot. A system with good headroom has all the power the speakers can handle, not just the bare minimum they need to get by. Having comfortable headroom gives you several benefits.

Dance club DJ booth

You'll need a system with lots of headroom for a crowded dance club.

With ample headroom, you should have all the volume you need when you're around five-to-seven out of 10. Pushing an amp to its limits — running it on 10 — can cause "clipping" distortion. The tops and bottoms of the signal waveforms are cut off (or “clipped”).

Clipping can damage your speakers. Some PA amplifiers have indicator lights to warn you when the signal is approaching the clipping point — these tiny lights have saved many a speaker. But having plenty of headroom is the best way to avoid clipping.

With robust headroom, your system will also have better dynamic range. The loud parts will sound just as good as the quiet parts. The bass parts will hit a lot harder without distorting.

Don't forget line-conditioning power protection

You'll get cleaner, clearer sound and protect your gear from power surges if you plug everything that needs AC power into a power conditioner.

What you need to know about the connections

Power amplifiers typically offer XLR and 1/4" inputs for connection to a mixing board or other audio source component.

Most amplifier manufacturers recommend using balanced XLR connections throughout the signal path. Balanced connections reject noise. They’re especially helpful where long cable runs are necessary.

You may also find RCA connections, which are more common on home audio components.

Speaker connections

You'll find three different kinds of amp output jacks on the back panels of most PA amplifiers:

speaker jack types

Speaker connection options — A) Speakon, B) Banana/binding posts, C) 1/4"

Speakon plugs offer the added security of a twist-and-lock connection.

Banana plugs/binding posts are more versatile. They accept bare wires, if the need arises.

When using 1/4" connections, make sure you use pro speaker cables with 1/4" plugs. Don’t use instrument cables, which have the same kind of plug, but aren’t designed to carry amplified audio signals.

THRU or line level outputs

Planning to use multiple amps in the same system? You’ll need amps that have line-level preamp “link” outputs. They send the mixing board’s signal on to the next amp in the chain.

These outputs are usually 1/4" and can also be used as inputs.

All about the knobs, buttons, lights, and display screens

Some PA amps are pretty brainy. You may find knobs, buttons, and indicators for the following:

Gain settings

Typically, the front of the amplifier will have a gain/level knob and signal level indicator for each channel. Colored lights indicate when the amp is clipping.

Frequency filters

Frequency filters let you tailor the output of an amp to suit the type of speakers it’s driving.

A high-pass filter (also known as a low-cut filter) lets you reduce the output of a speaker below a certain frequency. It lets the amp focus its power on the higher frequencies and not waste energy on the power-hungry bass frequencies.

This kind of filter helps to eliminate audio distractions such as bass rumble, wind noise, and microphone thumps. When you have a separate subwoofer handling the bass in your PA system, you’ll want to remove the deep bass from your main speakers. They’ll play louder, and without distortion.

A low-pass filter removes the high-frequencies from the amp’s output. Use the low-pass filter when the amp is driving a subwoofer.

A band-pass filter removes both lows and highs. Band-pass filters are good for fine-tuning the performance of your subwoofers.


Limiters are protection circuits that can help keep your amplifier from clipping and to prevent distortion in the sound. They help prevent distortion caused by an overdriven signal, a dropped microphone, or a short in an input jack.

Time alignment

Churches and theaters often have speakers along the side walls. These allow people in the middle and the back of the room to hear things just as well as the people up front. And you don’t have to turn the front speakers up too loud.

For your side speakers, you’ll need an amp with the ability to delay the output signal. A little delay will “time-align” the side speakers with the front speakers. The sound remains crisp and highly intelligible throughout the room.

Parametric EQ

Some amps have very sophisticated equalization capabilities to help you fine-tune your sound. These adjustments can be made via the front-panel buttons or (in some cases) with a connected computer. Features like this eliminate the need for racks full of outboard signal processors.


Want friendly, one-on-one help choosing the best amp (or amps!) for your PA system? Our expert Advisors can help. Call or chat with us today for free, personalized advice. Free lifetime tech support is included with every Crutchfield purchase.

  • Dale from Moses Lake

    Posted on 6/4/2021

    We are looking into a new PA system for our baseball field. I want to mount these on the side of the booth. Can you tell me what the best speakers would be and AMP? I am thinking three speakers and cost is an issue seeing we are a state fund school. Thanks

    Commenter image

    Ned Oldham from Crutchfield

    on 6/7/2021

    Thanks for asking, Dale. This link to our commercial A/V System Design page is where you can get in touch with one of our advisors, who can help you figure out the best system for your baseball field. From the same page, you can also choose fill out a system design request form.
  • Raymond Flores from San Diego

    Posted on 12/21/2020

    hello i just upgraded my speakers into Maggie 3.7i. right now, Mcintosh MC152 is driving it. Do you think, should i upgrade my power amp? If yes, what do you recommend fr my Maggie's speakers? thanks

    Commenter image

    Jim Richardson from Crutchfield

    on 12/22/2020

    Raymond, Thanks for your inquiry. For help with your system upgrades, please contact a Crutchfield advisor at 1-800-555-9369.
  • Rain from Tampa

    Posted on 12/6/2020

    I am a solo artist, like to play rock backing tracks via a PA with as close to live sound as possible while I play on top of it for gigs. Key metrics: * the ability to fit a room for sound would be cool (small, med, large). * on the fly adjustments (drums louder or softer, bass louder, etc) from stage. * be able to use for acoustic guitar and vocals sections with clarity. not savvy in this area so any recommendations appreciated. thanks in advance

    Commenter image

    Jim Richardson from Crutchfield

    on 12/7/2020

    Rain, Thanks for your interest in this article. Please contact a Crutchfield advisor to discuss your situation in depth. That's the best way to get a good system recommendation. Call 800-555-9369.
  • Larry from Bellingham

    Posted on 10/6/2019

    I just had the owner of a historic building, small to medium venue, call me about updating his audio system. He seemed to be interested in a completely wireless system. If that a possible is it a wise way to go. I'll wait for your response before proceeding with upgrades. Thank you in advance, Larry

    Commenter image

    Dominic DeVito from Crutchfield

    on 10/7/2019

    Hi Larry - Thanks for your question. We're hesitant to recommend trying to go "completely wireless" for any sort of PA system, because you're surely going to run into interference issues from cell phones and/or nearby Wi-Fi networks. An advisor should be in touch with you shortly to help you figure out the best system for your needs, or you can reach out to one via email, web chat, or phone.
  • David from Minneapolis

    Posted on 6/9/2019

    Hi, I'm looking for a 2 channel recommendation to power 4 - Martin Logan Motion 4i speakers at the same time and 1 -2 subwoofers (hoping to get away with only 1). The only device hooked up will be a sonos zone player and this will be for music only. Thanks!

    Commenter image

    Dominic DeVito from Crutchfield

    on 6/10/2019

    Hi David: Thanks for your inquiry. There's a bit more we need to know about your system before making any recommendations, so one of our advisors will be in contact with you shortly to make sure you get the right gear for your needs.
  • Antony

    Posted on 3/28/2019

    i need to power 10 speakers all at once for my church 6 are of one type and the other 4 are of another type. should i just get 2 smaller duel channel amps to run them duel channel putting 3 in parallel on the 6 set and the set of 4 as 2 parallel or is there anything out there to run 10 speakers

    Commenter image

    Dominic DeVito from Crutchfield

    on 3/29/2019

    Hi Antony - Without knowing what kind of speakers you have, I'm hestiant to give any advice here. An Advisor will be in touch with you via email to discuss what your options are for your system.
  • John Donohue from Highlands ranch co

    Posted on 9/9/2018

    I have a 4 zone system with the mains going to run off zone 1 on a marantz receiver. I want to use the 2nd zone preouts to drive an amp for the other 3 zones. The other zones have speakers that are 75 to 60w rms and higher for peak above 240w or so. The speaker wire runs are long tho at 34 to 77 ft. Would the xls 1002 be appropriate to drive that with a speaker selector in line? Or would another amp be better?

    Commenter image

    Dominic DeVito from Crutchfield

    on 9/10/2018

    Hi John: It's unclear what sort of system this is — if it's a 120-volt audio application, and you're using a Marantz home audio receiver for the first zone, the Crown amp seems like 1) a bit of overkill as far as wattage and 2) an odd choice if fidelity is your primary concern. There are too many variables to answer this question, so an Advisor will be in touch with you soon to try to find the right solution for your needs.
  • Commenter image

    Dominic DeVito from Crutchfield

    Posted on 7/19/2017

    Hi Bill - You definitely do not want to run amp 1 into amp 2. You'll want to connect each Crown amp to one of the bass cabinets. But that Crown amp should be sending 300 watts in stereo mode to each of those Kustom cabs, so before you go to all the trouble of running two amps, make sure that your two cabs are firing together in phase. If they are not, you'll be losing some serious bass. One other issue: the Crown is stable at 8 ohms in bridged mode, so if the Kustom cab is 4 ohms, you do not want to run a single cab with the Crown amp.

  • Bill Corbridge from College Station

    Posted on 7/16/2017

    Great article, but although you showed the multiple amps in a picture, I don't see a discussion of how to connect multiple amps together. For example I have a Crown 402 and two Kustom 215 speakers. It seems that this setup is a bit under powered, so I would like to add a second Crown 402 amp. Do I connect amp 1 to amp 2 and feed the speakers from amp 2, or do I have each amp power each speaker (or some other setup?). Thanks

  • olufemi from lagos

    Posted on 3/30/2017

    Great article.

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