Peng is correct. PS3 needs an HDMI for HD Audio. You can run an optical connection, but won't get HD Audio through Optical. Only DD.
Truthfully, and some may jump all over me for saying this, but I don't think PS3's are really best suited for sound quality. Sure, they are great all in one units, but they run very very hot and have a built in fan that is constantly running, which will affect your SQ.
For games, they are great. For SQ in movies and especially for CD listening, I think the new OPPO blu-ray is a much better solution. So yes, I'd buy one of each, but that's if you have the m both in your budget, which most of us don't these days with this economy!
As for the Rotel vs Arcam, I currently have a Rotel 1056 aside from the HDMI, I don't think they are very different in SQ. My Arcam arrives this week. I'll let you know how they compare. If the Arcam doesn't sound much better, I'll be disappointed!