Got the coax option in mine. I came from an 01b Audi A4 with the great BOSE system so am kind of picky...
Updated the speakers since I found the treble heavily distorted and mid-bass lacking in the original setup in the
CTR. Never expected to get any "deep bass" so am now considering a proper sub enclosure. The dealer strongly adviced NOT to bus the bassworks, and I understand why.
The dealer said to "run in" the speakers for 40h. Already approx 10h playing time and a noticeable difference from the original setup. They sound great! Highly recommended! Not as great as the Audi BOSE soundstaging and detail, but close. Now only lacking low-bass... =) Waiting eagerly for them to loosen completely!
Most likely you can get better value for money, but I personally was too convenient - its always nice to have things ok from the factory (for me anyway).