using PS3 with Pioneer HTS-GS1 receiver problem, PLZ HELP!

Ok my problem is rather complicated here it is. My setup is PS3 and Xbox 360 connected via HDMI video to Panasonic Viera S1 HDTV, my audio is digital optical from the each game system directly to my Pioneer HTS-GS1 receiver. The Xbox 360 works fine with 5.1 sound on everything. The PS3 works fine with 5.1 sound on Blu-Rays only, games are only 2 channel. When i go to audio settings on the ps3 i have the option of Dolby Digital 5.1, DTS 5.1, and 4 different linear 2 channel PCM, 2 of which are checked and greyed out so i cannot change them. None of this makes any since to me, i thought of running the sound through my hdmi to tv and tv out to reciever with optical, but my tv does not support the hdmi/optical conversion in 5.1. Does anyone have any idea what i can do here because i am stumped