Learned a lot in what must be a top-ten entry for longest post, thanks.

Like Tanstaafl, I'm not sure about some of your comments about class D amplifiers.

As I understand it, Class D amps have to use filtering to filter out the sampling garbage in ultra-sonic range. This is commonly done through coils between the output devices and speaker terminals. Big disadvantage is that, as a result, frequency response becomes dependent on the actual impedance of the speaker connected. So unless you have the exact right and constant impedance, you may experience exessive or dull highs

BTW, there is a true digital amplifier; not class D. The Tact Millenium accepts S/PDIF in and sounds truly awesome, in particular with serious High-end speakers.

There's some interesting "room-correction" stuff there too. Need a bigger wallet

Cas.