One other question...

When you set the level on the MacMini to that very small but usable one, how loud is it? Is the sound level comparable to what you'd get from a DVD player, for instance? Or do you have to really crank your Yamaha way up to hear it?

On my AppleTV, the loudest setting is roughly what I expect from a DVD player. In other words, it seems like the AppleTV's volume is just a function of limiting the output.

M80v2 | VP150v2 | QS8v2
SVS Pci+ 20-39
Emotiva UMC-1 & LPA-1
M22ti + T-Amp, in the Office