I've done a lot of experimenting with different gear on my desktop. It will be hard to do better than the D4 with an iDecco. It's a fantastic match. I tried the Harbeth P3ESR which sounded nice, but were a too big. The Peachtree DS4.5 is good, but sounds best with the grilles removed. The D4s have a less boxy sound on vocals than the DS4.5s.
The D4s are supported by a REL T5 subwoofer, which makes an excellent match.
The D4s are supported by a REL T5 subwoofer, which makes an excellent match.