Well, the combo is delightful for a small space. I am using the pair in my bedroom which is pretty decent size. I'd recommend the unit for any smaller room, say 13x11 or less. The pairing images like a dream. Sweet.
The Peacetree Integrated can drive larger speakers and will stay. The D4, sadly, will not be staying as the room is too large. The speakers that will stay are Kef Ref 101/3s which where probably the same price or more than the D4s, but in 1992 dollars. (so I'd say the D4s compare extremely well with much high dollar gear)
One person has dibs on the D4, so well see if he is still interested. Stay tuned.