I guess you don’t understand that with efficiency comes a plethora of other advantages:Cost. Well, that’s certainly true: cost reduction for the manufacturers who are simply reaping the benefit in profit margins. Yup, they can put $400 worth of parts and labor into a 15lb amp and charge many thousands. If these cost savings were being passed along to the end-user then I’d agree.
1: Size
2: Cost
3: lower energy consumption
4: Lower heat
5: Less EMI (conducted and radiated)
And due to the above advantages, possibilities open up the simply aren’t possible with conventional class A amps. Such as
1: Tight integration with DSP and DAC on same board to eliminate extensive sound quality losses from outboard DAC’s, cables, connections, preamps, buffer stages, output stages etc.
2: We can now fit absolute SOTA cool running DSP/DAC/Amp combos right in speakers to eliminate passive crossovers and speaker cables. The amp DSP can be custom tuned for each driver individually, to optimize for distortion, over-excursion, and saturation.
3: We can eliminate having to have separate enclosures for each component. And the costs involved with paying for multiple enclosures. While at the same time drastically shortening the signal path, and optimizing each sub-section to work together in absolute harmony.
The list goes on but that’s a good start.
Lower energy consumption, yeah, that’s basically what one would infer from the term "efficiency." Where’s Capatain Obvious when you need him?
Lower heat: well, some folks like the extra heat of their class A amps in the winter. Unless I’m shoehorning an amp into an Ikea cube, heat is a total non-issue.
Less EMI with placing the DAC inside the box??? Weird.