I listened to both a 6900 and an C220/MC252 combo. Based on what I heard, it did not take long to decide for the latter for only $1200 extra (the separate combo was on sale that day, but I would have probably gone for it anyway).
The C220 tube pre is the best I've heard in that price range (try both the 6900 and the C220 with headphones and a familiar CD and you'll see what I mean).