Originally Posted by Bruce Embry
I’m old school, and anything other than Class A or Class A/B simplify put is not High Fidelity.
That's pretty old-school. First off we now have a goodly bunch of Class G/H amps which can be as linear as class AB. We also now know that Class A can easily have poorer linearity than the same resources deployed in Class AB, or H.
High-end speaker designers spend a lot of time designing cross-over networks to minimize frequency shifts/phase-shifts that can color the music. And then the Class-D amp which contains filters on the output will interact with the cross-over network in the speakers.
You're sitting on the cusp of a statement that all Call D amplifiers are the same which has to be false. They actually have fairly significant differences in design features that address the issue that you raise.
The ongoing increases in switching frequency makes the power amp output filter less of an issue. Furthermore class AB amps which you have deified, can have output filters. Finally, some Class D amps put the output filter inside the global feedback loop, which can make a difference.
When you start adding filters on top of more filters to drive speakers you are going to mess up the sound of music.
Again a black and white statement when the real world is shades of gray as just explained As I pointed out above, even Class AB amps usually put filters on top of filters. Most class AB amps have series inductor/resistor networks to improve stability with tough loads. This filter is usually cutting in in the top octave of the normal 20-20K audio band. . If filters are always bad then there are few if any good amplifiers.
Driving speakers properly requires high damping factors (low impudence in the amplifiers)
Again infinite decreases in amplifier source impedance don't provide infinite audible benefits. The law of diminishing returns is alive and well!
high speed amplification, and power supplies that provide the amount of currents/voltage to keep the music waveform intact (low distortion).
Low distortion is always a good thing, but again to a point. High speed transistors and beefy power supplies are not required for good damping factors.