I know your question wasn't directed for me, but I think I suffer of the same thing... mine its just a common, cheap home theater... using RCA cables...
And GT5 is on Small Theater setting.
Probably, not much hope for me.
No, it's not the supposed quality of the system that I'm interested in, more the possibility that people have their game set to 5.1 speakers but are listening through their stereo TV speakers (for example). Sounds daft, but sometimes it just doesn't occur to people that this distinction actually matters / exists; I think the HDMI output on the PS3 is audio hardware agnostic, and it's possible the game simply defaults to 5.1 if it's "available".
I use stereo headphones, but I've set the console and game up accordingly, and I, too, use the small theatre setting. (If you can appreciate / prefer the difference the small theatre setting makes, I'd suspect your hardware is probably "adequate".)
It's also true to say the game is better suited to "surround sound", as the stereo mix was too flat before the "sound improvements" and now it's too "polar", to my ears (especially with headphones.)
I cannot really comment on individual "virtual surround" implementations; some are good, though, but the most convincing methods are usually highly dependent on listener position. Try the stereo and normal 5.1 mix in the game options to see which you prefer (the virtual mix is
weird on normal 5.1 hardware, but it might be a Sony thing).
There
should be a timbral difference between the front and rear aspects, since PD use two separate (directional) sound sources per car, although, in my opinion, the lack of intake wastes the potential of the "engine" source somewhat, meaning it's usually just the mechanical noise, which is what people seem to liken to vacuum cleaners.
The sample accuracy, with regards to a given car sounding like it has the "correct" engine type, for instance, is a separate issue, probably related to direction within the sound team.
