you need to be looking at going for quality 24bit/96khz analogue outputs. spdif isnt capable of carrying DD+ or Dolby TrueHD. i dont know about blueray but as far as HD-DVD goes, DD+ gets downsampled to 640k DD (still very good, mind) and in my case TrueHD doesn't work at all. my amp thinks its stereo pcm, albeit stereo pcm at 2mb/sec lol.
Using analogue, as im sure you know, you wont have that problem.