I had one for a while as well, and went to an Active Linn system (3x5105's w/5140's) and never looked back. The 4004 Mk II is a solid amp, but the linn stuff is so much smoother in the upper mids and highs. I lost all the graininess I heard with the Aragon when I upgraded, the bass changed slightly, somewhat less punch, but again, this area also became more natural with the Linn system.
FWIW my old 4004 is still in the family, it powers the woofers of my brothers ML Monoliths III's. It's up to you if you keep it or not, but I personally am very happy I did upgrade.
FWIW my old 4004 is still in the family, it powers the woofers of my brothers ML Monoliths III's. It's up to you if you keep it or not, but I personally am very happy I did upgrade.