Wonder if the amp in this is more powerful than the E11? E11 does a pretty poor job of driving the HD-600, so I imagine this will have no chance. I think someone said this could drive their K400, so that's good enough for me. Might get this or the Bithead.

That was me. The K400/K500 on high gain were given enough volume and didn't sound bad. Having written that I do know how a fully driven old school AKG can sound. The E10 can give you a decent taste of what those AKGs can sound like.
Regarding the Bithead, the Headroom products and especially in the desktop range do strike me as interesting. But for simple desktop use the E10 is worth the money and I do appreciate the line out...