Power Consumption of Hi Fi at different volumes

I am trying to ‘estimate’ how much electricity I am using when using the hifi (Naim Uniti Star with Spendor A4).

The Uniti Star has an AB amp and is specified at 70W per channel into 8ohms (my speakers). It says typical power consumption is 130W.

I listen to music at 3 different volume settings:
Low (20%), Med (40%) and High (60%)


  1. Would I use less electricity at the low volume setting?
  2. Approx how much power consumption would I use at the Low, Med and High settings?

The power consumption between low, med, high is negligible. The major part of the consumption is to have it active. Playing only consumes a few watts. In my system with 272, 555PSDR, 300DR, 300PS and some other stuff it consume 55w just being on and 3-5w extra when playing music (loud). Having my system on 8766h per year (24/7) would cost me 116GBP per year (currently at 0.24GPB per kWh in Sweden). I would guesstimate your Star consumes around 20-30w.

Thanks Slamdam. But Naim in their Specification manual says it consumes typically 130W

Get yourself a cheap power consumption meter from Amazon. You can then check each component in different modes of use. It’s the only way you’ll get accurate’ish figures.


Hm, that sounds a lot for a one box solution. Not sure why a Star would consume so much more than my 272 (preamp, dac, streamer) + 555PSDR + 300DR + Lumin streamer + EE8 switch.

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500 has a quiescent of below 40W playing music takes it up to 50W at about 8 o’clock. Meross mss310 are useful around the house to understand your energy consumption. You may get surprised by what you discover.

The rest of mine is about 50W rising a few Watts when playing.


My assumptions are - If I have 70W per channel the total max output for the amp is 140W. As it is an A/B amplifier I assume the efficiency is 50% so max theoretical input power would be approx 280W?

Indeed, there’s an automotive saying “test don’t guess”. :slightly_smiling_face:


I can assure you my measurements are correct, but I could not listen at max output so it’s not very relevant.


Agree😀 probably why they say typical consumption is 130W


I obtained this graph from ‘audioholics .com’ which shows the characteristic of a typical class ab amplifier. From this if I assume I typically listen at 30% of max output power ie 42W, at this point the efficiency is 30% so my input power is 140W, which is close to the 130W typical power consumption that Naim gave. It would be nice to have the actual graph for the Naim product

Unless you sometimes play extremely loudly with inefficient speakers the difference in electrical energy consumption between quiet and loud listening really is pretty minimal:

If your speakers are a fairly average sensitivity at, say, 88dB/W, and you sit, say, 4m away in a not too echoey room, and listen at a very moderate 76dB average level, your amp would be delivering only about 1 W (0.5W per channel, so maybe 1.2-1.5 W of electricity more than when Idle. (If you sit closer to the speakers less power would be used for the same loudness at your ears.) Things go up more when you get really loud - with the same speaker/room setup a 90dB average sound level, would mean your amp would be delivering about 25W (12.5W per channel), and maybe using 40-60W more electricity than when the music stops. More than a short period at that level is ear damaging territory - so thus level of power consumption shouldn’t be happening for long.

Does anyone here know how much electricity a 555PS uses just switched on please? ATB Peter

There is a whole thread on power consumption somewhere on the forum

My 555PSDR powering a 272 consume around 30W when on. (Measured)

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The actual consumption measurements I’ve done on my system (posted elsewhere on the forum) neither support your assumptions nor conclusions!

As others have said - buy a cheap meter and measure it.



The 130W power consumption is a value given by Naim in their specification for the Uniti Star (see attached)

These were the assumptions and conclusions I was referring to.

So why not simply assume Naim’s spec is right, with actual expected to fluctuate slightly around tgat figure, but, as has been indicated by more than one responder, not by enough to be significant in terms of your energy usage at different practical volume levels?

Not sure what is incorrect Ebor. The 50% efficiency is for AB amps (see the graph I posted). The 70W per channel were max output power supplied by Naim (see the specification I attached). I agree in reality you would not listen at max power though.