b&o-upgrade-without-mmi-navigation-plus

This may / may not help, but a relative has the B&O system in her A4 Avant, it sounds incredible. ****s all over the bose system that I have in my A3. It makes my stereo sound boomy and muddy (which it is).

Now, regarding the surround sound, I can't imagine it would make much difference because when I play with the settings in her car and turn the surround sound off, it makes a little difference. But it might be different when the entire unit is different.

Also, I think this is in the wrong forum, should be in the 8V section.

You need to remember that almost all music tracks whether CD, MP3, or WAV are usually only recorded in stereo 2.0 (left and right channels). Playing this media through any 5.1 system will only divide the sound to the extra channels, not essentially true surround sound, and usually loses sound quality.
Try it on any home cinema system, play a CD and it always default to stereo output.