How to Choose an Amplifier for your Speakers

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There’s nothing quite like finally getting your own home speaker system fully set up. But as the old adage goes; a speaker is only as good as the amplifier it’s used with.

Okay, I made that up – but it’s still pretty true. The amplifier is a critical piece of tech that you need to give your speaker life. Whether it’s for a guitar or for your in wall subwoofers, getting the right amp is definitely the right thing to do. But which amplifier should you choose for your home speakers? Well, here are the best ways that you can choose an amplifier to match your speakers.

How to Choose an Amplifier for your Speakers

When you’re deciding which amplifier you’re going to use for your speakers, there are many different things for you to take into account. This includes;

  1. Impedance
  2. Power
  3. THD+N
  4. Connectivity
  5. Crosstalk


Undoubtedly the most important thing you’re going to have to think about when considering what speakers and amp you should get together is the impedance. Quite simply, this is the current resistance and capacity of the electrical current running through the circuit of your speakers; check this guide of 4 vs 8 ohm speakers if you want to understand a little more about how this actually works.

Anyway, the main thing that you need to know is that they need to match. If you have 4 ohm speakers, then you’re going to need to get a 4 ohm amp that delivers enough power to these speakers if you want them to play properly.

Now let me be clear – this isn’t a hard rule that 4 ohm speakers must play on 4 ohm amp, and 8 ohm speakers must be on an 8 ohm amp. The ohm’s, or impedence rating, is quite simply a scale of how much resistance there really is. This means that a set of 4 ohm speakers will perform better at louder volumes if they’re linked up to a 4 ohm amp. They’ll still work with an 8 ohm amp, but at louder volumes, you’ll start to notice a difference between them.

This is the first thing to take into consideration when purchasing an amp to match your speakers, and it’s quite an easy one for us to follow as well.


Now we’ve covered the impedance of your speakers, we’re also going to want to take a look at the power of your speakers too. This can be another factor to think about when you’re on the hunt for a new amplifier to match your speakers. A speakers power rating is actually much like a car – it’s the maximum that it can perform at. This means that if you was to play it at it’s maximum, like a car, you might cause it damage. Whilst it’s the maximum capabilities, it’s not the most sensible thing to do.

So instead of just looking at the power (wattage) of our speaker and being done with it, we need to look at it’s power ratings, which is the amount it can cope with for an extended period of time. This is typically shown in continuous power, which is the measurements that it can cope with continuously.

What does this mean for our amp? Well, generally we’re going to want to try and find an amp that has double the continuous power rating of our speakers. So if the speakers have a CR rating of 300 watts, then we want an amp with at least double this amount. Simple.


The THD+N of our amplifier is another thing that we need to take into account. This is the most common methods that we use to measure audio signals, and it’s a way we can work out the performance of our audio. Along with frequency response, it’s one of the most important things that we measure within audio.

Essentially, this looks at the impurities that are outputted by your audio system due to distortion. Firstly, we measure the first level of the frequency band – it’s signal, which is made up of it’s tone, it’s harmonics and it’s noise, as well as it’s non-harmonic tones. Then, the signal is removed by a notch filter, and we look at the second level here, which is the residual of the aforementioned criteria. Not too easy to understand, I know.

Essentially, a THD+N measurement is a good way to know whether there’s a problem with your system, but it can’t really determine what exactly the cause of the distortion may be. So, the distortion is definitely something that you’re going to want to factor into your decision when purchasing an amp.


Something else that’s worth thinking about with your amplifier is it’s connectivity, and how you’re going to connect it to your speakers. Generally, you’re going to want to use speaker wire to connect the two of them together, but this isn’t always the case – it’ll all depend on the speakers that you’re using. Sonos even released their wireless amp recently, which is an example of what the future may hold for amp connectivity.


Something else that’s worth thinking about with any set of wireless speakers is crosstalk. Sometimes you might see this referred to as leakage, or leakage between the different channels. Nowadays it’s much less of a problem with amplifiers and speakers, but it was once considered much more of a problem when setting your speakers up.

Essentially, this is just how much of each different left and right speaker might be mixed into the different channel. An amplifiers job is to separate out the signals between each of the speakers, but sometimes this signal can get crossed between the two. The result? Well, this can seriously effect the sound coming out of your speakers.


In conclusion, when you’re picking the right amplifier for your speakers, there are various different things you’ll want to think about.

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