I don't really like the HD600, and don't find them particularly detailed. I'd sell them and get Sony MDR-V6's or MDR-7506's -- definitely the detail freak's friend. But yeah, if you insist on the amp and not the headphones (I can see why, the Senns are in the top 10 most comfortable headphones ever anywhere), they do scale well. A good amp and source will definitely bring things more to your liking.
I have heard X-CAN sound very detailed, but it was with a Sony CD-3000, and I believe it was modded, but hell if I know what the mods were. Caps, I think.
EDIT: Okay, confirmed, caps and opamps. He followed the recipe posted on head-fi for the v2. So, since you have the v1, I would look around for that; barring that, I'd use the recipe for the v2 as a loose guide (I.E. make equivalent changes), but if you don't understand what that means, I'd suggest going to Pinkie.