Amplifier knowledge part 1: the basics

Amplifier knowledge part 1: the basics

By Angus .

Amplifier knowledge part 1: the basics

You’ve arrived here because you’re thinking about buying an amplifier, but don’t really know what’s required beyond knowing that you need an amplifier!

Well, like that uncle at the Christmas table that has an extremely specialised job that no-one else understands (or cares to), we’re here to give you all the the information you need and then some, delivered with the flaccid, defeated humour of a man who’s already been through a bottle and a half of cream sherry and three divorces.

Seriously though, an amplifier is the beating heart of every true stereo setup. Without it, speakers lie dormant and turntables and CD players are left mute with nothing to push their audio signal into your lounge room.

In the simplest terms, the role of an amplifier is self-evident it’s name, it’s there to amplify the signal it receives from a source and send it to speakers via an electrical current.

But it performs other duties too, being the control station that takes all of your different audio sources and delivers them to your speakers in thrilling stereo sound.

This work includes converting digital information from a CD player or streaming device and transforming them into analog (audible) signals, amplifying your turntable’s signal to required levels and even offering you the option of altering that sound to your taste by adjusting certain frequencies.

You’ve undoubtedly used devices with amplifiers before, you just may not have been aware of it. Car stereos, TVs, your smartphone or laptop, Bluetooth speaker; all of these devices use some form of amplification to boost an audio signal to audible levels. Here’s a couple of examples at both ends of the spectrum:

A basic amplifier board. It has a single 3.5mm audio input jack and a Bluetooth receiver and offers 10 watts of power per channel. So you’re getting a single analog input, Bluetooth streaming and the ability to power the most undemanding of speakers. It’s an amplifier by name, but its capabilities are relatively limited.


A McIntosh MC2KW 1-Channel Solid State Amplifier. This will deliver 2,000 watts to a single speaker which is sufficient for just about anything on the home hifi market, but you would need two amps; one to power each speaker. Each one requires you to part ways with $86,000AUD, and you can’t actually plug any sources into it. More on this later.

So, an entry-level amplifier will take a signal, increase its volume, and push it to a pair of speakers. An excellent amplifier can deliver your music, TV and films in a way that is so realistic and lifelike that you’ll wonder how you ever survived with your undersized Bluetooth speaker that got dropped in the pool that time in high school.

Immersive is a word that’s thrown around a lot in relation to audio, and with good reason, investing in a quality amplifier and speakers has the ability to immerse you in a song or scene in a way that lets you forget the world for a time.

We think that ability to completely lose oneself in the comfort of your lounge room is something worth getting to know, so we’ve set out to guide you towards that experience.

The way one brand varies from another can be significant, and there are choices many and varied that need to be made before you decide which amplifier is right for you. Here are some things to consider:

What sources am I going to feed it?

Or, more simply, which components that I have around the house do I want to plug into my amplifier? Answering this question is a good starting point and can refine your options considerably.

Say you’re buying a turntable and you want an amplifier to plug it in to. You’ll just need the one input for said turntable right? Let’s think bigger.

Most TVs don’t come equipped with terrific sound, with many manufacturers prioritising form over function. Surely it’d sound a little more impressive coming through those nice speakers you just spent your rent money on?

In that case, an optical input or two on the amplifier is desirable (assuming your TV has optical audio output, which most do). And what about that CD player your brother left you before he moved to Berlin? Check its outputs, it might have analog (red and white) or digital (coaxial or optical) outputs so let’s account for it too.

Some amplifier brands (including Rotel, which you can you find in our store) include USB inputs, meaning you can plug your computer and in some cases a smartphone in and play music that way, and even charge your phone too.

Bluetooth might also be an essential capability, because sometimes you just want to kick back with slightly-too-big glass of red at the end of the day, throw something on your phone and zone out.


The rear panel of a Rotel A12. Rotel equip their amplifiers with enough inputs for a full suite of hifi and home cinema components. A phono stage, several auxiliary inputs, optical, coaxial, USB, Bluetooth, and two sets of speaker outputs are all on offer.


Before making any decisions on which amp to buy, give some serious thought to all of the devices you might like get a better sound out of around your house. You might be surprised at how versatile an amplifier can be.

What sort of amplifier do I need for the speakers I have?

There’s a few factors to consider here, but at the beginning of your hifi journey we think price makes for a sound guidepost. More affordable speakers under say, $1,000 a pair tend not to need too much power to get the best sound out of them, and likewise cheaper amplifiers tend not to have particularly high power ratings. You can always check the manual if you have one, and if not a quick Google search should furnish you with a product manual. Haven't got any speakers yet? Check out our selection.

When we talk about power ratings in an amplifier we’re talking about watts per channel, which is an indicator of how much power an amplifier pushes to a speaker when transmitting that delicate audio signal.

A good speaker manufacturer like Monitor Audio will give you an indication in their manual of what sort of power ratings their speakers can handle. Their best-selling Bronze 2s, for example, for which they suggest somewhere between 30-100 watts per channel.

How much space do I have?

Until recently - and in some instances this is still the case - people worked under the assumption that in the case of amplifiers bigger was better. This simply isn’t true, and since you might be relatively new to this hifi game you have the benefit of a lack of preconceptions.

If you’re living in a relatively small space and thinking of upgrading from a small Bluetooth speaker you’ll be pleased to know that you can power a system effortlessly with some fairly small components, courtesy of Pro-Ject Audio Systems, who offer a large range of “micro” hifi components.

So before you get stuck in the mindset that a hifi system has to be a beastly thing that occupies a full third of your living room, take a look at their range.


Head over to part 2 for some more learning and a short form buying guide that'll introduce you to some key differences between brands and models.