I have a 2012 X5 with premium stereo and after listening to the system playing CDs have concluded that the 'Surround' option muddies the sound quite a bit. Listening without the surround engaged unveiled the clarity of the system. I also agee with a previous poster who said to use he equlizer to primarily demphasize the frequencies that are too prominent. Do not boost the lower frequences as it will rob power from the system and you will increase distortion and increase muddiness. To me, the system seems base heavy when flat and benefits from decrease in the 100 and 200 hz bands. I boosted the 10khz band a bit and decresed 2khz a very small amount. On other music such as FM and satellite, those settings may not suit, so I am still tweaking.

Bottom line is that the system is NOT limited by the speakers in term of clarity when you disengage to surround button.

Maybe someone else knows what type of material is improved using the surround?