I've decided to fit an Alpine CD changer in my boot rather than the OEM VW one which goes in the arm rest. The Alpine has a 20 bit processor with an excellent D/A converter.
I have an OEM RNS 510* sat nav, Kenwood amps, Pioneer underseat Sub, Morel 6.5", 5.5" mid/bass units and Morel silk dome tweeters. The overall sound is superb, but the CD player could be improved. Hence the Alpine.
BTW, the RNS on it's own sounds rubbish as did the OEM speakers. I also did not like the Dynaudio sound, though this is excellent value for money..
I mainly play Classical music so a decent system, I feel, is mandatory. Techno also finds it's way in sometimes! It's cost an arm and a leg so far.
Must stop after this!