Posted on Thu, 06 Nov, 2014
Posted by Peter

valve amp

One thing you can say about the world of hi-fi today is just how many options there are to choose from. With all of this choice – right at your fingertips – it’s no wonder choosing an amplifier can be a daunting task! Where do you start? Which ‘class’ do you chose? What is a ‘class’? How many watts do you need? and do valves sound better?

… those are just the tip of the iceberg! Amplification can be a minefield… until now. We at Audio Affair have put together a blog which offers simple and practical advice, guiding you to your perfect amp. And here it is!

Making the Investment

Let’s face it, if you are looking to purchase a dedicated audio amplifier, then you are serious about the investment in you musical enjoyment. I don’t mean a purely financial investment either; the enjoyment of music is a emotional experience – one which can augment good times, relive past times and help with just about anything life can throw at you. We at AA – hold a deep belief that the music is the key and an amplifier is this catalyst for greater musical appreciation.

Cracking the Code

As soon as you start reading the reviews or dipping in the forums you’re blinded by technical terms, integrated, mono blocks, the list goes on, lets have a look at some of the key terms with simple “real world” examples:


arcam-a19-front Probably the simplest form of amplifier on the market. Plug in your speakers and source (CD, turntable etc.) and turn up the volume! An integrated amp is all your amplification needs in one box – key examples are the Arcam A19 and our entry-level favourite the Yamaha A-S501!

Why choose an integrated?

–  Simple to use on box solution
–  Often works out a cheaper investment to the below
–  More choice than power amplifiers and monoblocks

Power Amplifier

naim-audio-nap-500-front A power amplifier can been seen most simply as all muscle no brain, i.e. no volume control. All it does it take the signal, amplifies it and then sends it to the speaker. That’s it. In order to use a power amplifier you will need a preamp to control the volume such as this.

Why Choose a Power Amplifier?

– Dedicated amplification for loudspeakers
– No inbuilt pre-amplifier to interfere for delicate signal paths
– Greater power owed to a larger power transformer – a result of removing the volume control


mb845ii-meter-covers-off Take the amps above and split them in two (one amp for each speaker) and you have monoblocks! One block drives one speaker. With this set up, you will still need the preamplifier mentioned above, or a similar one.

Why choose Monoblocks over a stereo power amplifier?

– The ultimate expression of amplifier implementation
– Each block has its own dedicated power supply, transformer and signal path
– The increased power allows you drive a speaker more efficiently so speakers that require more power (often seen in higher end monitor type speakers) can be given the juice they need.
– They look really cool
– True bi-amping (two amps, two speakers and a four to four plug cable between each)

These are the different amplifier types we offer put in the simplest form, if you have a more involved question about anything above then please do not hesitate to get in touch.

Choosing your Class

There are many types of amplifier out there which are often banded around on the forums and reviews with little explanation to for what they actually are. From Class A to G, choosing the right class isn’t always obvious. So here is a breakdown of the main classes.

Class A

000005-02Comprising of valve amplifiers and Class A transistor designs – such as those from the Sugden range – Class A uses 100% percent of the input signal which often results in a warm and what can been described as a more human presentation. The problem with Class A is the limited output power and the fact they get quite warm (do not touch valves!)

When to choose a Class A?

A decision clearly offset by the aesthetics of valve kit, it is a statement and a talking point in the home, they sound beautiful as well, especially if you listen to classical of vocal/acoustics music. Your loudspeaker will also be a defining factor, you will need one with good level of sensitivity (measured in Decibels). We can of course make recommendations for you! I will discuss power ratios a little further down.

Class A/B

Class-AB-Amplifier-OperationDue to the restrictions of Class A amplifiers, designers often employ Class B as well. For example, you may get one or two watts in Class A and the rest Class B. Put simply: with Class A/B amplification you get most of the warmth of Class A with the improved efficiency and power of a Class B design.

When to choose Class A/B?

The vast majority of loudspeakers are not super-efficient (beyond 92dB). Monitor-type loudspeakers, for instance, tend to be less efficient due a flatter frequency response (how a speaker can recreate a signal as it should be). In real world terms, if you are looking for an amplifier with valve warmth but enough kick to drive larger floorstanders, then Class A/B maybe the way forward. They can also sound faster and cleaner than valve designs (in some areas), however sound is relative so trust your ears – what you like is right for you. If you are set on valves (and why not) but require some extra grunt, Icon Audio may have the solution. Their Stereo 60s – being self biasing – produce 60w in ultra linear and is more than capable of driving the majority of speakers on the market, check it out!

Class D


A modern  super efficient form of amplification seen on some newer high end kit such as the Roksan Oxygene – very useful due to its size – which improves the aesthetics of design without limiting sound quality.

When to Choose class D?

Looks aside, a Class D is powerful, clean and precise. With many serious manufacturers opting for Class D designs, now may the time to get involved.

More Power!

One of the questions I am asked a lot is ‘what is the power output (measured in Watts)?’. Logically the power output should be reflective of the loudspeaker you are trying to drive vs. the size of the room. For example, if you choose a twenty Watt valve amplifier, a speaker with an 85dB sensitivity will not be driven adequately – leaving a limp unsophisticated sound. Ideally, if your speaker is 90dB, for instance then you should choose an amp with around a 25-100w output. If your speaker is 86dB’s or below, look at amps that start at around 75w. More power does not always mean a better amplifier.

One final item to look out for is connectivity, ensuring you have the correct number of inputs for your sources is an important factor. Some amps will have phono input for turntables and some will not. The higher-end you go, the likelihood of this becomes less. This is due to the fact that outbound phono stages will give a better response than those inside your amplifier!


So, we hope that by reading this you will have a greater understanding of the vast field of amplification and thus will be one step closer to the thing that bought you here in the first place: choosing your new amp. Just remember, it is important to remember you ears are right. After all it may look great, but how does it sound? When you listen to your favourite tracks, let your ears –  and heart – be the judge.

By the way, if you’re still confused – or just want to talk it through, give us a call and we’ll be happy to steer you in the right direction.

Happy listening!