TX-SR605 Onkyo's Surround Sound Processing on a stereo signal sent through HDMI

[shedeus]

Hi all

I recently purchased onkyo's tx-sr605 and ps3 and have run into an audio snag i cannot figure out. Granted, I am VERY new to home theater...

I am currently transmitting via bitsream over HDMI, and all is well in regards to DVD and video playback of optical media.

I do however have both audio/video media saved on the PS3 hard drive that only has stereo channels embedded (home videos taken from camcorder, MP3's, etc.) or more often a CD that typically only has 2 audio tracks.

My dilemna lies in the fact that when my PS3 is hooked up to the onkyo, the only surround sounds options are multichannel or direct through HDMI. It seems through HDMI, I can no longer access Onkyo's sound processing to convert my 2 channel audio into 7.1 via Dolby Pro Logic IIx for example.

Why is this?

Even more perplexing is when resetting all my audio connections through optical (sans HDMI audio), I have complete access to these surround sound options in addition to keeping DTS 5.1 etc (but i do believe i'll lose HD surround audio). I dont want to keep switching between optical and HDMI because quite simply it's a hassle, and i firmly believe there's a better solution and perhaps i'm missing something. HDMI was supposed to get rid of this switching back and forth, no?

Where is the flaw in my audio setup that makes it impossible to choose anything but direct or multichannel surround options on my onkyo when utilizing HDMI to process 2 channel/stereo audio?

many thanks in advance!!