Sony CDC-C90. Alpine S, 7982, 7939, 59609815, 9855. Eclipse 8443, 8455. Clarion DR'S.
I've ran some pretty expensive decks but never used them to their potential for ACTIVE setups, just passive. They all sounded good but I was never satisfied with them in PASSIVE setups until I took a chance and tried the Ken wood D. In PASSIVE, the Kenwood just seems to integrate so much better than all the decks I've owned previously. Not thin like Alpine, not warm like Sony ES or Clarion, not digital like Eclipse. Mind you, some of those sonic characteristics are subject to personal taste. The 01D is just musical and full bodied. A real surprise.
Funny thing is that I'm now in the active experimental stage and will be looking at a new deck -- again.