Efficiency of most class D amplifiers are among the specs if not at amplifier manufacturing web site hen at original vendor e.g. B&O web site.
For example, our amplifier, Musician III has efficiency of 92%.
Efficiency has nothing to do with the stability of the power supply (and sound quality, in principle) as Almarg pointed out. Where its important are two areas: a) your utility bill and b) the size and weight of your amplifier.
For example, we have 1300VA Transformer in PSU and efficiency is 92% then "effective transformer" is in essence 1300 x 0.92 = 1195VA
If we compare it with typical class A amplifier where efficiency is about 25% then it needs:
1195 VA / 0.25 = 4800 VA (real life) Transformer. What it does with such transformer its different matter but it adds weight to the amp; and multiple additional heatsinks add cost and weight as well.
Yet, many class A amplifiers are simply magnificent and many are simply ear-piercing machines.
Simon
For example, our amplifier, Musician III has efficiency of 92%.
Efficiency has nothing to do with the stability of the power supply (and sound quality, in principle) as Almarg pointed out. Where its important are two areas: a) your utility bill and b) the size and weight of your amplifier.
For example, we have 1300VA Transformer in PSU and efficiency is 92% then "effective transformer" is in essence 1300 x 0.92 = 1195VA
If we compare it with typical class A amplifier where efficiency is about 25% then it needs:
1195 VA / 0.25 = 4800 VA (real life) Transformer. What it does with such transformer its different matter but it adds weight to the amp; and multiple additional heatsinks add cost and weight as well.
Yet, many class A amplifiers are simply magnificent and many are simply ear-piercing machines.
Simon