I know that if you listen to something else, then put on nice cans it makes you appreciate your set more: I have a nice set of tower speakers (Wharfedale Evo2-30s), but after having a good session with my HD650s, the Wharfedales just don't sound nearly as good anymore, it takes a few hours before my mind forgets the sound of the HD650s and I can enjoy my towers again!
Exact same thing here!
Atm I use a cheap Class-D amplifier from eBay to drive my Epos Epic 5 speakers, the sound is still good but not nearly as good as my HD650s, if you forget about soundstage of course :P
Piano solos in example sound harsh, unrealistic on the speakers but delightful and subtle on the HD650.
Still saving for a real integrated ... I'd like a Vincent SV-227 (hybrid), maybe the Creek Evo2 if I can't save enough.
Now of course Intel just released the NUC, which I absolutely need for my audio rig and to replace the WDTV Live. NEED IT => Even less money for the amplifier, or longer wait...