I guess if I heard it side by side I could tell the diff. In my 2001 M5, the DSP setting was clearly marked in the menu and turning it on and off made a huge difference.

digiteye and x5fx,

So do the iDrive menus for you guys have certain settings? I do have the equalizer and only a choice between stereo and surround

rezf,

I had the "normal" speaker system in the car which I have thrown away the next week after delivery.
Then I had a 3rd party audiophile system built in which is stereo for the time being. I need no surround, as only super audio CDs come in surround - and I doubt the OEM CD player can play that plus I dont watch DVD-s in the car.

My 3rd party DSP supports surround, so in case if I change my mind later there will be the option to add surround to my system.

This change does not show in iDrive settings, the DSP has its own software for setting EQ and other sound characteristics, e.g. distance from speakers. You can adjust these settings using your laptop or Palm via bluetooth - and for me it was enough to set them once (how many times do you really need to play with the equalizer?)

The whole thing costs a lot less than the OEM Premium option and it has far better sound (all OEM speakers are made by Philips... enough said)

Oh - and a very important information: it is "stealth" built, meaning you cannot see anything inside the car, all parts are hidden. You just hear it.