Type D amps are what you're looking for

That is a very nicely written tutorial.

I take issue with only one part of it -- where you proselytize about the benefits of a Class-D amplifier.

In my (admittedly limited) experience, Class D amps are good for one thing only: getting maximum amount of noise out of a subwoofer with minimum amount of input power.

A class D amplifier gets its efficiency by aggressively filtering out the higher frequencies at the pre-amp stage. This makes a Class D amplifier ideal for a subwoofer amplifier, because you don't want those high frequencies going to your subs anyway, so why waste power generating them.

This also makes a Class D amplifier somewhat less than ideal for a subwoofer amplifier, because without some of those higher frequencies, all you are left with is the boom; you lose the tight crispness and the warmth that a subwoofer can produce if you get brave enough to raise the crossover point above the normal 80-100 Hz. I cross my subwoofers (dual 10"s in a common enclosure) at about 800-900Hz.

And of course for running a complete stereo system with speakers ranging from 1" (or smaller) up to six inches (plus, of course, your subwoofer(s)) a Class D amplifier is exactly what you do not want if sound quality is even remotely important to you.

Now, I could be mistaken about all this -- this is just a summary of my own personal experiences -- and would be quite interested and not the least displeased to be proven wrong.

tanstaafl.