I take it then that your PS3 is one of the early, 60gb models - the later 40gb & 80gb units had this feature stripped (as well as the dream engine for playing PS2 games).

Most SACD's are actually hybrid discs that have a "normal" CD layer too - you would need to ensure you were actually sending the multi-channel data to your BS3 (I'm not sure how the PS3 handles this, presumably multi-channel PCM, but I don't know).

...........................and then the speculation starts, you sound like you have read the thread that "raged" here a month or so ago. There is a question mark (not to mention considerable disagreement) about how comprehensively the BS3 handles multi-channel "high-"definition" audio.

I fear it is all about to break out again😮😂

Yes, there is a good argument that the sound will be significantly better than CD, although it's also dependent on the DACs used. If you run digital audio out into the BeoSystem 3, then I expect you could experience sound significantly better than CD. If you rely on the PS3's built-in decoders then the outcome would probably be quite different.

I am not actually sure what would happen in the signal flow and processing of SACD audio. SACD is 1-bit audio and has a sample rate of just over 2 MHz - it follows completely different standards to CD, DVD-A etc...

hmmm ok - i didn't realise that the new ones didn't have the ability to play SACD

yes the couple of discs i've tried have not only 2 channel SACD & 'normal' CD encoding but also 5.1 SACD as an option. and yes I eh... 'studied' the previous HD audio vs BS3 thread - but that's my point -

as i'm an audio person more than a movie person - could i (in theory) buy a nice pair of BeoLab 9s connected to a BeoVision 8 (yes 8) and hook up a PS3, to get the best in audio quality?

No. I would get a fantastic quality preamp and fantastic quality DAC if you were really wanting to use BeoLab 9s to their potential...