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With the rising cost of electricity, not to mention the environmental effects of energy consumption, you may be wondering just how ‘green’ your h-fi system can be. And there are other considerations, too, not least of which is the ability of some hi-fi components to chuck out plenty of heat – handy in cold weather, but a pain when we’re having a heatwave. Either way. it’s a sign that the equipment is wasting the energy that  it should be using to play music.

And it can be extreme: I recently reviewed a valve amplifier which was drawing a meagre 350W from the mains, while some socking great high-end amplifiers I tested a few months back drew 10kW maximum – and they were mono, so two were needed. To put that in some context, that means the valve amplifier would cost you 7p an hour to run, while a pair of those monster monoblocs would be chewing through electricity at the rate of £6 an hour. Oh, and that valve amp heated the room so efficiently that, even with the outside temperature at what we now consider a very mild 23C or so, the listening room got too hot for comfort after only a couple of hours. But then with the cover over the valves humming away at more than 70C, what did I expect?

In denial

Now, the old argument used to be ‘if you can afford to buy such products – £30,000 for the valve amp, or £250,000 for those big mono amplifiers – then you can afford to pay the power bills’. Possibly a once reasonable assumption, but totally out of step these days, given the spiralling cost of energy and our increased awareness of the environmental consequences of almost everything we do.

Yet, while most hi-fi equipment plays a fairly trivial part in our total household energy consumption – well, unless you have some of those power-gobbling designs I mentioned above – but it still contributes, although of course you can always switch it into standby, or even better turn it off, when you’re not listening, rather than leaving it on all the time.

Standby for action

Or can you? Some high-end hi-fi components don’t have a standby or power switch on their front panels, and are designed to be left permanently powered. I have some of those in my system, and can tell you that unplugging stuff to move things around leads to a period of time before the system settles again. And we’re not talking hours to get full performance back, but days…

All sounds a bit grim, but if you’re buying new hi-fi components, you can do your bit to cut your consumption – and your costs. For a start, check whether the products have a standby mode, and that they only consume a Watt or less when this is on. An exception to this will be network-connected devices, which will need to keep some circuitry running to maintain the connection, allowing software updates to take place overnight, or letting them ‘wake up’ as soon as you want to play something using Bluetooth or Apple AirPlay. If you still think that consumption is too much, simply turn the products off at the mains, but be prepared for a short wait when you turn them back on before everything is good to go for your listening session.

Class structure

The kind of amplifier you buy – and it’s amplifiers that use the most power – will also have a major impact on your energy consumption. 

Class A amplifiers, which shed the power they’re not using to play music as heat, are the most inefficient: they consume the same amount of power whether playing or simply idling. The Class AB amps still in many hi-fi amplifiers and systems are much more efficient, as they commonly only use the power required to play the music – although they still consume power when idling. However, increasing numbers of amps are using what are known as Class D amplifiers, which are much more efficient.

A couple of misconceptions have held back Class D in the past: one is that the ‘D’ stands for ‘digital’, which it doesn’t, and the other is that Class D doesn’t deliver the same sound quality as older ‘conventional’ amplifiers. There’s been a lot of work done on Class D and its variants by companies such as Dutch-based Hypex – read more at if you want to dig deeper – and its amp modules are now found in studios, PA systems, and hi-fi. Companies such as NAD and Marantz have adopted Hypex technologies, and super good their products sound, too.

Finally, save energy by taking a ‘holistic’ approach to your system: choose speakers with higher sensitivity, and you don’t need as much amplifier power to drive them to room-filling levels. Read the sensitivity figures in our reviews, and realise that every 3dB in that sensitivity figure represents a halving of the power required to reach a certain level. So, a speaker with a sensitivity of 85dB/W/m – the sound pressure measured at one metre from the speaker for one Watt (or 2.83V) of input – will require twice as much amp power for a given level as one rated at 88dB. Choose your speakers with this in mind, and with an eye to more efficient amp technologies, and you can specify a less powerful amplifier, allowing you to listen with a big green grin.