Capacitor-less amps

Yes.

It is also possible to make a crossover for the speaker where the tweeter has no capacitor in series with it. It uses an inductor across the tweeter. The drawback is that such a crossover wastes a lot of power in a resistor needed to avoid a short circuit on the amp at low frequency.

A DC-coupled amp is really a DC power supply with analog command input, and a high slew rate. In fact, many years ago a power supply manufacturer demonstrated his product at a trade show by playing music through it. Subsequently, some audio amp manufacturers took this approach.

I have a couple of old Kenwood L07M amps that are direct coupled, and they do sound really good dispite their age (or should I say "vintage").

John_tracy...Get real! If power supply capacitors were in the signal path the amp's HF rolloff would be about 0.0001 Hz!

Aball...Yep. I don't know what I was thinking. I guess that the point I was making is that the PS capacitors are such huge values, compared with coupling capacitors, that they would look like a short circuit to an audio signal.

John_tracy...But it doesn't pass through it.