Picking the best amp can be a pretty hairy procedure. What inputs and outputs do I need? Is it right for my speakers? Is it going to give me the best sound? Here at TMS, those are the kind of questions we get a real kick out of answering. And whether you're after a dedicated stereo amp for your home hifi system, or something a little more fully-featured, we can help you pick the right one. Because it's not just about going for the best amp money can buy - it's also about picking the amp that is right for you. We'll not only go into the basics, but talk about the factors you need to know to make the right choice, as well as breaking down the jargon and talking about how to match an amp to your speakers. It sounds complicated - but we guarantee that by the end of this guide, you'll have everything you need. Scout's honor.
 


For most people, a volume knob and a couple of inputs will be sufficient | Martin Thomas

What Exactly Is An Amp?

First off, let’s start with the simple bits - the amplifier is the component of your soundsystem that not only powers your speakers, but lets you select the sound source and raise and lower the volume. In it's simplest form - the stereo amp - it handles two channels, the left and the right, both of which make up the audio you here. You can apply anything in this guide to amplifiers in general, which come in a rainbow of colors and types, but we're going to focus on stereo amps for simplicity.

Of course, most amps handle passive speakers - speakers which receive their power from the amp itself. You wouldn’t and you shouldn’t need to connect an amp to active speakers. These are also known as powered speakers, because each of them would already have an internal amp connected and matched to the driver (internal speaker). Similarly, if you are already using a powered A/V receiver, you wouldn’t need an external amp. Every rule has an exception, though, and for the instances where you might be looking to expand an existing system, you could actually hook an additional amp and speakers. '

Yeah, we know. We’ll explain all this below.


Amp Types:

Before we go on, let's break down the various types of amps you'll encounter. Knowing which is which will help you make the right choice as to which one you need.

The first thing you need to know is that every amp you encounter will have two components: a preamp and power amp. Together, these take the raw signal from your sound source, which is at a level too low for you to hear, and amplify it, making it loud enough to listen to and imbuing it with some good qualities, like richness and depth. Now, you can get individual preamps and power amps, and mix-and-match them – a good example would be the Yamaha Aventage MX-A5000 power amp with the Yamaha Aventage CX-A5100 preamp. Those are two fantastic (albeit expensive) pieces of audio equipment that, together, make up your amplification system.

The advantage of this – or the Aventage, perhaps – is that building a system with separate preamp and power amp is expensive. It's far more common, and far easier on the wallet, to go for something called an integrated amp, which combines both types of amplifiers – pre-and power – in a single box. This is usually a lot cheaper and a lot more convenient. Most affordable stereo amps these days are integrated, and they are by far the easiest solution when you're looking to choose a nap. A perfect example is the Peachtree Audio nova300 (full review here) – don't be put off if you can't afford that one, as there are plenty of other good ones for a fraction of the cost.

So now that we've got the amp internals nailed down, let's talk about a couple of other distinctions you need to know about.

Standalone Stereo Amps, of which the nova300 is one, are the ones needed to power an audio source into a pair of speakers. These are usually quite straightforward to operate - all you need to do, technically, is connect speakers and your sound source, and go! Of course, many stereo amps have additional useful features, such as multiple input ports - and some, like the Marantz in the photo below, have things like CD players and network receivers.

Powered A/V Receivers (a receiver with an integrated amp) are the most popular type for home theater installations. These can be stereo or multichannel affairs (5.1, 7.1, etc.), and handle video as well as audio.

PA Amps are very similar in design to stereo hifi amps. They just have a volume control for each channel, but the difference is that they are spec’d to deliver huge power - from 250 watts all the way up to 3000 watts per channel. They are designed for pro music venue applications - anything from clubs, music venues and stadium shows. You probably don’t need to worry about these.

Tube Amplifiers are essentially like regular stereo amps but using military-grade vacuum tubes in their internal output circuitry. Tubes are famed for their exquisite portrayal of dynamics (quiet and loud) and may be that’s why you’ll see tube amps mostly in high end audiophile setups. They are distinct from solid state amps, which use electronics. This is more of an amp sub-type - so you could have a standalone stereo amp that runs on tubes.

Then there are Mono and Multi-Channel Amps. Amps can also be distinguished by their number of channels - a mono amp would have one channel only, stereo - two channels and surround amps can vary enormously - from six channels (5.1) up to 15 (13.2) and possibly more.

Marantz MCR611 - a stereo amp with a built in CD player and network receiver. Handy! | The Master Switch

What Do I Need To Know To Choose One?

Choosing a new amp would probably start with just an idea - something like: right, this is gonna be for my living room, I‘ve got a couple of speakers here, and I'm going to be using them movies/music/videogames/whatever.

There are a couple of things that are obviously quite important here. How many speakers do you have? Do you have a subwoofer? What is your sound source? USB from your laptop? A turntable? A media server? Once you know what's going in and coming out of your amp, you can work out how many features you need, without having to spend money on the ones you don't.

That's important, because amplifier prices can escalate quickly. If all you need is a single box to drive a set of mid-level speakers, then you can probably get away with nothing more than a set of inputs and a volume control. If you've got more demanding speakers, then you may need a slightly pricier amp to get the best out of them. The price also goes up if you want more than two channels, such as an additional subwoofer output.

It doesn't help that manufacturers tend to throw a hell of a lot of jargon into the mix, hoping to dazzle you. When in doubt, come check back on this site. We are here to highlight the things you really need to know about.

One of those things is how to match an amplifier with a pair of speakers, in terms of making sure that the power the amplifier puts out is able to be taken up by the speakers and used in an effective way. Their driver size, the power handling and the number of speakers you’d be using are the hard facts which would determine the main specs of your power amp - namely, wattage and impedance (don’t freak out - we’ll go into these in a little more detail below). Once you know these necessary spec figures, you could then sort the contenders by price to match your wallet.

For the majority of people, the easiest way of getting a decent hi-fi system is still to purchase a system-in-a-box (as in: an amp with separate speakers, all in one package) since everything is pre-configured and pretty much ready to play. But: opting for a stand-alone stereo amp would make a lot of sense if you are just amplifying your phone or PC/Mac, or a turntable. And to make sure you have an amp that can drive your speakers to their fullest potential - which, after all, is what this is all about - you're going to need to match them. That, really, is the most important thing.

The amp should be able to deliver, without a struggle, what the speakers can handle at their optimal state of performance - in other words, when they are loud as hell. Audio signals are essentially like waves, and the high point, or the peak, is the crucial bit in terms of how audio signals affect amps and speakers. The loudest sections of a song should not present a problem - for neither the speakers, nor the amp. 

If they do (and let’s start with the speakers), it would be when the amp is pushing audio ‘peaks’ well above the handling capacity of a speaker, and…well, let’s just say you will hear it. It sounds like a tearing, flapping distortion noise. This can result in blown speakers, even after a short while. So yeah - don’t do it.

The second scenario of amp/speakers mismatch would be when the loudest audio peaks challenge the amp instead. This would be in the case of the amp being underpowered for the connected speakers, and the problem will manifest itself in signal clipping - the level light indicators (every amp has them) clipping into the red, basically saying: “That’s it, you’ve pushed me too hard, I can’t really handle that, can’t feed those speakers with the level you’re asking me to…oh God, I’m dying, send help.” 

This would lead to the amp heating up until it goes bang. Neither blown speakers nor blown amps are a nice thing to experience, and it’s not particularly safe either.

We have a full guide to just this, if you're interested, but it comes down to the following simple rule: You need to find out your speakers' continuous or RMS power (the power they put out at a 'normal' volume) and their peak or dynamic power (the loudest they can go). Then you need to pick an amp that can handle both. You'll be able find these stats on the spec sheet for any given amp or set of speakers.

Of course, there's a little more to it than that...
Matching an amp to a set of speakers is super-important | The Master Switch

Impedance Matching

We mention and describe the term impedance quite possibly in every TMS piece - whether it’s about headphones or speakers. It describes drivability - how easily a piece of gear handles and responds to an electrical signal. Possibly the most confusing fact about impedance is that unlike wattage, the lower the impedance figure, the more optimal power you get out of the equipment. 

Impedance is a bit like how a garden hose delivers water to the far end. A constant flow of water would result in a different spraying power, depending whether you have a narrower or a wider hose. A much wider hose would give you less pressure, and a thinner one would be sending out a powerful, high-pressure spray.

Just like with wattage, you’d need to match your speakers’ impedance to that of the amp, and luckily, most hifi-grade speakers and amps are designed to easily match. Any matching you do has to happen at the same impedance - which is important, as speakers and amps often give power figures for different impedances

It’s (slightly) more complex than that, but only slightly. Let us just stress that if your speakers have a really low impedance, they shouldn’t be connected to an amp with a higher one. The other way is generally OK (low amp impedance, high speaker impedance) but in this case you’d be using only a fraction of the amp’s full potential. This is because impedance is directly linked to wattage - in the real world, an amp that pushes 400 watts at 2 ohms (Ω) would be able to push only half that - 200 watts at 4 ohms. It would be halved yet again - down to a 100 watts if connected to a 8 ohm speaker. 

Here’s an example. If you have a stereo amp pushing 200W at 4 ohms, you can actually connect it to a pair of speakers running at, say, 25W/8 ohms each. But you’d be utilising only a fraction of the amp’s power. To get the full 200 watts working, you could in fact add another pair of 8 ohm speakers as a ‘daisy chain’, e.g connected to the speaker outlets of the first pair of speakers. In this way, each side (or channel) of the amp would be feeding two speakers running at 8 ohms each and this would be equal to running a 4 ohm speaker on each amp’s side. 

This approach is often used in bars and commercial installations, where more spread and room coverage is needed. Choosing a low-impedance amp would allow stringing 2 and sometimes 3 speakers one after another on the same amp channel…but hey, this is something you probably don’t have to worry about.

The example our writer Derrick Lilly gives in the above-mentioned guide is as follows. "If you need 100 watts out of your amp at 8 ohms, pump it into an 8-ohm speaker that can handle 200 watts of Continuous Power. This should give you plenty of headroom for when the impedance drops, causing those Dynamic Power peaks, and a little more room to spread those gooey peanut butter vibes."

And we do love gooey peanut butter vibes...

There’s another scenario, which is if you have a preamp. Preamps, as their name suggests, come before the amp acting as ‘hubs’ for all of your audio sources, allowing you to switch between them at will. Think of a DJ Mixer, which may have many different sources (turntables, a laptop) plugged into it.

They also ensure that the levels fed to the input section of the power amp are optimal and correct - neither too hot, nor too quiet. If using a preamp, the way to connect it would be by sending the left and right outputs of the device into the left and right inputs of your power amp and bingo, you’re set.

Preamps can come in many guises, such as dedicated hifi preamp, a (non-powered) A/V Receiver, or, as we said,  a DJ or line mixer.

Getting The Most Out Of Your Amp

First things first: setting your levels correctly. The maximum volume you should take it to should be roughly three quarters on the dial, or roughly 3 o’clock (assuming that your amp’s max dial level is roughly around 5 o’clock). The amp will be pushing plenty of clean, continuous power to the speakers and the remaining one quarter of power is left for handling the highest-volume peaks of the material. This is how pros set up amps and not only in home set ups, but for big event installations as well, using 6000 watt beasts. It really works.

You’ll know when a system has hit the sweet spot - you’ll have no distortion, and everything will sound crystal clear at any listening level. This is quite easily achieved with bundled packages - the ‘home theater in a box’ type or similar - and it's a real thrill when you handle it yourself.

Believe it or not, some people still like to emulate the glorious Jamaican sound system-type setups in their living room. Starting with a source audio player (CD/Blu-ray), the signal would go into a preamp, followed by a graphic equalizer, which plugs onto a 3-way crossover unit (splitting the signal into three frequency bands - bass, mids and tops, each of which have their own amplifier), fed into three amps, pumping a (still stereo) mix for the listening pleasures of the whole neighborhood… 


Ah, the joys of speaker binding posts... | The Master Switch

Cheat Sheet

Wattage: The power rating and capacity of amps and speakers. 

RMS Power. The wattage measure of continuous power that an amplifier can output, or a speaker can handle.

Peak Power: Normally referring to speakers, if their continuous (RMS power) handling is 100 watts, their Peak Power handling is typically four times that- 400 watts. 

dB: Decibels. A measure of loudness

Impedance: A value for signal resistance. With high impedance, when only a small current is allowed through and vice versa

Ohm(Ω): The unit of measuring impedance (electrical resistance)
 

Three Great Amps You Can Buy Right Now:

Rega Elex-R ($1100)

Rega Elex-RIt might not be a looker, but Rega’s amp is one of our favourites. It has absolutely flawless sound, as well as a flawless pedigree, and really does get the job done.

It may be a little bit overkill for those just starting out, but if you’re looking for an upgrade to an existing system (and don’t mind a slightly dodgy remote) then this is the one you want. It may be a little tricky to track down - they're based in the UK - but it's well worth it.
 

Topping TP23 ($90)

Topping TP23Ideal for those just starting out. At less than hundred dollars, the TP23 offers a barebones but still very good experience, and is dead simple to set up and use. Just plug and play.

It’s not going to trouble the big dogs, but for newcomers, it’s perfect. Most of the time, home hifi setups don't require heavy duty amps, so a small, affordable one could be perfect - although its sound quality won't match the likes of the Rega.


PS Audio Sprout ($499) 

PS Audio SproutThe cute-as-a-button Sprout comes from a terrific audio marque. Doesn’t have a huge amount of power, but the small setups, it works really well.

Plus, the sound is just superb: rich and full, with absolutely terrific dynamics. Even sometime after release, this remains one of our favourites.


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