Since you say that movies aren't a priority, would sticking with stereo be a possibility? I'm of the beleif that a richly developed 2 channel system (left, right, and especially depth) can provide just about as much acoustical enjoyment as surround.
To configure that setup, I imagine that like many DVD players, the PS3 and/or AppleTV may have an option to mix down the mutli-channel audio to 2 channel which it would then route to the optical outputs. Of course then you'd have to decide which optical gets attached to the 7520's single optical input
David
iTunes 7,PowerMac G4 733, Mac OS X 10.4.11, Airport Express, Beresford TC-7520 (Dual LM4562NAs) MLC5/6 clipped, 36K and 100nf cap mod, Behringer EP2000, Cambridge Soundworks Tower II