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7 mistakes to avoid with your stereo amplifier

7 mistakes to avoid with your stereo amplifier
(Image credit: Copland)

We all make mistakes with our hi-fi, whether it's as minor as placing your speakers too far apart or as calamitous as knocking them over and denting their tweeter.

In a rush to get your system up and running and your music blaring out in front of you, it is just as easy to mistakenly overlook key parts of a stereo amplifier's ideal set-up or features, or fail to fully consider the optimal way in which it could work with the rest of your system.

Below is a short list of simple things to avoid with your amplifier – a list that we imagine will only serve as a reminder for many but will hopefully be handy new advice for others too.

1. Don’t use digital just because it’s there

Integrated amplifiers and preamplifiers are increasingly supporting digital connections as the prevalence and popularity of digital sources increases. But the digital-to-analogue (DAC) circuitry isn't always as well engineered as the analogue sections, so if, for example, you have a CD player with both analogue and digital outputs, we would try both ways of connecting it to your amp to see which sounds better and thus which component in the chain has the higher-performing DAC.

Similarly, if you’re looking to upgrade your stereo amplifier, don’t buy one with digital connections, or Bluetooth for that matter, if you don’t need it. Part of an amplifier’s costs – always relayed to the buyer to some extent, of course – are going to be wasted. You’ll be paying for a convenience you don’t need, and you might get more performance-per-pound value going for an all-analogue model. You can always buy an outboard DAC if you change your mind down the line, and we generally find their performance trumps that of an integrated DAC anyway.

If you do want to use digital, think about whether to go coaxial or optical if your source/amp pairing gives you the choice. Coaxial digital uses electricity to transmit audio, while optical uses laser light to transfer signals. In our experience, the former connection tends to sound slightly better and also has a greater bandwidth available, meaning it can support higher quality audio up to 24-bit/192kHz whereas optical is usually restricted to 96kHz.

2. Don’t overlook digital filters

If your stereo amplifier is digital-friendly, it might well have a handful of digital filters that you can cycle through – they’re commonly variations of ‘fast’, ‘slow’, ‘linear phase' or 'minimum phase’. To put it very crudely, digital filters are the final part of digital-to-analogue conversion and work to reconstruct the waveform of the original signal by trying, in different ways, to remove the aliases (ghost images) of the signal that are inherently caused in the process. 

In our experience, switching between various filters doesn’t make a huge world of audible difference, but there are subtle sonic variations that may suit your taste or system better, so it's well worth experimenting.

3. Don’t disregard system matching

An amplifier’s synergy with the pair of stereo speakers it is connected to is vitally important. The electrical compatibility between an amp and a pair of speakers lives or dies on three elements: an amp’s power output (how many watts it can feed to the speaker), a speaker's impedance characteristics (how difficult the speaker is for the amp to drive, measured in ohms) and a speaker’s sensitivity (how loud a speaker will go for a given input, measured in dB).

You don’t want to be in a situation where an amplifier isn’t powerful enough to drive the speakers properly – this can result in a lack of dynamics and punch in the sound at best, and a pair of damaged tweeters at worse. Perhaps counterintuitively, a weaker amp driven to distortion is more likely to damage a pair of speakers than a really powerful amplifier driving them hard. It's the distortion that does the damage, particularly to the tweeter.

If you want your system to play louder, go for a more sensitive pair of speakers rather than a more powerful amplifier. That’s because an amplifier’s output has to double to match a 3dB increase in speaker sensitivity.

You should also consider the tonal characteristics of other components in your system, as, for example, if something has a lean tonal balance, it shouldn’t ideally be paired with something else with a lean balance.

4. Don't think balanced is always better

All stereo amplifiers have RCA line-level analogue inputs, though some – especially those higher up the price spectrum – might also have three-pin XLR analogue inputs that carry balanced audio signals. 

A balanced connection's main advantage is that it is good at rejecting electrical noise and therefore is typically effective when used in electrically noisy environments or over very long cable runs. That said, balanced operation doesn't always sound better, especially outside of true high-end territory – it all depends on how well the balanced circuitry in an amp has been designed.

If your amplifier has both XLR and RCA connections, we would try both out before settling on a long-term preference.

5. Avoid placing it on any old surface

The surface your stereo amp sits on can make the world of difference to its performance. Generally speaking, glass shelving tends to encourage a more forward sound, while wooden supports typically result in a warmer and more rounded balance. More important than material, however, is that the surface it’s placed on is rigid, level and low-resonance – and therefore able to minimise the amount of disruptive vibration transferred to the amplifier.

All that power under its hood can build up quite a temperature, so it’s also important to give an amp a few inches of breathing space from a wall or rack to stop it from running too hot or overheating.

6. Avoid keeping the display on

A small thing but it's not unusual for any piece of equipment with an electrical display to sound better with that display turned off. That’s because the display can create some electrical noise that could interfere with the sound. 

If you don’t need it on, which is likely with a stereo amplifier as it often only shows input and volume information, turn it off if the option is there.

7. Avoid scrimping on cabling

As a general rule, we recommend spending around 10 to 15 per cent of your hi-fi system cost on cabling – interconnect audio cables that connect sources and amplifiers, and speaker cables that connect amplifiers to speakers.

Even budget electronics will sound better with some good interconnects, though the audible difference cabling makes usually does increase as the system's price (and therefore sonic transparency) does. In the case of a stereo amp, upgrading the supplied mains cable could also be worth considering.

Once they are all hooked up, avoid placing mains and signal cables too close to each other, too, as performance can suffer.

MORE:

The best stereo amplifiers you can buy

7 reasons why a DAC could be your music purchase of the year

The best 19 stereo amplifiers of What Hi-Fi?'s lifetime

Becky is the managing editor of What Hi-Fi? and, since her recent move to Melbourne, also the editor of Australian Hi-Fi magazine. During her eight years in the hi-fi industry, she has been fortunate enough to travel the world to report on the biggest and most exciting brands in hi-fi and consumer tech (and has had the jetlag and hangovers to remember them by). In her spare time, Becky can often be found running, watching Liverpool FC and horror movies, and hunting for gluten-free cake.

  • talaerts
    2 remarks.

    1. Regarding "not needing digital inputs if your old amp didn't have them" - it depends. If your sources are rather old then a good recent DAC in your amp may sound subtly better. Only subtly, ad you need revealing speakers, but it's there.

    2. regarding analog interconnects: I solder my own; using good professional microphone cable. The 2 core conductors are connected to the RCA centre and outside (being the 0); and the shielding is connected ONLY to ONE side's RCA outside. This provides a decent rejection of interference, not like balanced but it helps. I remember this trick from my studies decades ago, but can't calculate it anymore :-)
    Reply
  • manicm
    All very well saying 'rather get a more sensitive speaker than a more powerful amp' when the truth is there are very few truly sensitive speakers, especially European designed ones. Or go for Klipsch which may not be to everyone's taste.

    Sometimes WHF borders on the maverick side of expert advice.
    Reply
  • Sliced Bread
    manicm said:
    All very well saying 'rather get a more sensitive speaker than a more powerful amp' when the truth is there are very few truly sensitive speakers, especially European designed ones. Or go for Klipsch which may not be to everyone's taste.

    Sometimes WHF borders on the maverick side of expert advice.
    Having just replaced my speakers I agree regarding sensitivity. A higher sensitivity speaker was on my wish list, but there are so few around the choice narrows significantly. I actually ended up buying less sensitive speakers in the end as they were the ones I preferred once all factors were considered.

    That said; if you can find a pair that suits you, I would take WHF’s advice as it opens up the amplifier options.
    Reply
  • Sliced Bread
    Not to over Labour the point, but sensitive speakers tend to be the larger models in their respective ranges, so they often don’t suit smaller or even medium rooms. There are exceptions though.
    Reply
  • acgingersnaps
    What an article. 5, 6 and 7 are bonkers and have no basis in fact.

    "The surface your stereo amp sits on can make the world of difference to its performance. Generally speaking, glass shelving tends to encourage a more forward sound, while wooden supports typically result in a warmer and more rounded balance"!!!!

    Literally impossible.
    Reply