Whoa there Mr. Fancy Amp Pants, the best amp isn't going to make up for that $20 Monster Cab-- LOL, just kidding.
I do take it that the Monster Cable works then? Probably sticks out a little bit, but the cans do accept the shank?
I inadvertently discovered a way to make the 591 sound INCREDIBLY GOOD last night. I was given a pair of truly craptastic headphones to see if I could salvage them through some simple modding (foam removal, damping, etc.). And while I could easily alter the profile, the crap cans never sounded anything close to acceptable. No matter what, it was going to remain some shade of thin and sibilant.
However, I threw on the 591 afterwards for some recovery. It was like sliding into a warm bath of sound. It was great! Matter of fact, the 591 never sounded so good. Never know what you've got until its gone I guess.
Maybe that was that a factor all along... we didn't cleanse our palate before sliding into these? It was a while ago, but I'm pretty sure I was listening to a pair of Yogas (not a Fischer rebrand, another completely different model) and it had exceptional clarity for a simple pair of closed cans. Then I moved into the 591 without skipping a beat really. Might not have been sufficiently objective in my subjectivity? What were you listening to RIGHT before these? The P3 I think...quite a bit of difference there in clarity and detail I'd wager.
Or maybe I'm just really reaching and grasping at straws now?