I don’t bother with an amp for my home theater, and you shouldn’t either

• Why would you want an amplifier for a home theater?
• Why you probably don’t need a dedicated amp
• What should you look for in a separate amp?

When they embark on a hobby, some people have a habit of wanting to buy all the possible equipment they might need — or think they need — right away. It’s well-meaning, either out of enthusiasm or a worry about being prepared, but too often the consequence is that people end up buying some of the wrong things, or spending too much money. You can imagine how this applies to the home theater space — it may be how so many shoppers got tricked into buying gold-plated HDMI cables.

I fell for this myself when I got into electric unicycles, buying safety gear that was both more and less than I needed. But focusing on the home theater space again, a concern you might have is whether you need a dedicated amplifier, which is a part of some audiophile setups. The answer is almost certainly no, for reasons that are more complex than you might think.

Why would you want an amplifier for a home theater?

The obvious and less obvious answers

The purpose the average Joe or Jane understands is boosting the power of audio signals on the way to your speakers. Broadly speaking, some sort of amplification is unavoidable, since the signals coming out of your TV are only really meant to carry data.

There’s more going on, though. Even when a signal is reasonably strong, a dedicated amp can improve clarity at higher volume levels. This is valuable in a home theater context, considering that movies, shows, and games often have multiple audio layers competing with each other, such as music and dialogue. Indeed an amp may sometimes be the answer to distortion and clipping when volume spikes, say during an intense gunfight.

Even when a signal is reasonably strong, a dedicated amp can improve clarity at higher volume levels.

Passive speakers are completely dependent on outside amps. They’re not particularly mainstream these days, but they do have fans in the audiophile community for their lightness, and enabling mix-and-match customization of a home theater setup. Without an amp, a passive speaker is going to emit no sound at all, or something so weak that it’s useless.

That’s just about it, but one minor incentive to buy an amp is relieving the load on your receiver, if you have one. In theory, your receiver should stay cooler and more efficient.

Why you probably don’t need a dedicated amp

With a few exceptions

If you’re using a soundbar, a pair of standard stereo speakers, or a relatively simple surround-sound setup, a separate amp is likely redundant. Why? Congratulations — you should already have an amp, perhaps several. That’s because the majority of speakers are “active,” incorporating not just an amp but a power supply. If a speaker has its own volume knob or power cord, you can tell that it’s an active model.

The benefit of this is that your setup is kept simple and (relatively) flexible. There’s less equipment to install, and you can use the speakers with just about anything as long as they have compatible inputs. There may be some hassle finding places to plug them in, but extension cords and powerstrips are going to be cheaper than any amp-based configuration.

Speaker-based amps do have their limitations, particularly in more advanced surround-sound setups that require a receiver. But all receivers have built-in amps, so a lot of enthusiasts can stop there as long as their receiver meets the necessary specs — more on those in a moment. They include support for the number of channels you intend to use, and enough RMS (sustained) power to equal or exceed what all your speakers demand.

All receivers have built-in amps, so a lot of enthusiasts can stop there as long as their receiver meets the necessary specs.

There are a few reasons why you might buy a dedicated amp even if you’ve got a receiver and you’re not using passive speakers. If you’re still encountering issues with low volume, or clipping and distortion at higher volumes, an amp may be the ticket. In fact if you’re really taking the idea of a home theater literally — with overwhelming sound, maybe even stadium seating — an amp might be essential to prevent problems.

It should definitely be a consideration if you’re planning to build a large-scale Dolby Atmos setup, typically anything including or over 7.1.4 mark. That number translates into seven horizontal channels, a subwoofer, and four ceiling channels, and there’s a good chance your receiver won’t be able to handle all that on its own. If so, an amp can cope with the excess channels.

One final exception is if you have low-sensitivity speakers. Despite the name, these can actually provide increased accuracy and deeper bass, thanks to rigid internal components. The tradeoff is that they need more wattage — often, a lot more wattage — to sound correct. The average person should generally avoid low-sensitivity models, given that there are plenty of amazing high-sensitivity speakers that aren’t as thirsty.

What should you look for in a separate amp?

Some key specs

To elaborate, the most fundamental requirement is support for the number of channels you’re hooking up. This doesn’t just mean ports — it also means a watts-per-channel (WPC) rating that matches or beats what each speaker needs. Typically this is between 50 and 150W, but some low-sensitivity speakers may call for 200W or more. You should plan for overhead, as it’s important that your speakers be able to handle volume spikes without trouble.

An amp also needs to match the impedence of speakers. There’s a more technical explanation of the concept, but all you really need to know is that it’s measured in ohms. Many amps are geared for 8 ohms. There’s a chance that some high-caliber speakers will need an amp capable of 4 ohms.

You probably don’t even need a receiver if you’ve got a 5.1- or 7.1-channel configuration based around a soundbar.

Accuracy is indicated by a couple of stats, the first being total harmonic distortion (THD). Smaller THD is naturally better, with superior amps potentially falling under 0.05%. Just as important though is frequency response range. On any speaker system, this dictates how much of the highs and lows in your audio can be reproduced. Bass down to 20Hz and treble up to 20kHz will be plenty for any movie.

There are other possible considerations, such as trigger outputs (in volts) for turning components on and off, and whether an amp supports HDMI ARC or eARC. The signal-to-noise (SNR) ratio is another. This is measured in decibels (dB), and the higher that number, the less risk there is of audible hums or hissing. Digital amps can regularly top 100dB, so your real concern should be making sure the other components you’re using live up to that.

Wrapping up, I just want to reiterate the point that you probably don’t need a separate amp. When you’re shopping, check for the specs above on a receiver, and stick to that purchase if it lines up with your system. You probably don’t even need a receiver if you’ve got a 5.1- or 7.1-channel configuration based around a soundbar.