Well, the shoot out went off with out too many casualties. The group listened to a custom made tube OTL amp hooked up to Senn 600's and did an AB' between that amp, a Headroom Max amp and my MF X Can V3 with rolled in NOS 6922's. Using the same Marantz CD source and with various other cans, including AKG 702's, Beyerdynamics ( not sure of the model, Sam/c1ferrrari step in here), Senn 650's, Senn 600s with and without the Cardas upgrade cable, Grado SR125i's,Grado Sr60i's, Senn 551's and lastly Senn 201's we came to the conclusion that the headphone amps ability to drive high or low impedance was the main issue. My fave was the Senn 600's with Cardas cabling on the custom OTL amp, but many others preferred the Grado's on my MF X Can's. But as Sam just posted, the other thing that was evident was the harmony between certain 'phones and specific amps. An example of this, was I thought his Beyerdynamics worked great on my MF X Can's and not as well on the custom OTL amp.
One thing I came away with was that regardless of which cans I was listening to, the 'gestalt' of listening to cans vs. a full high end speaker system left me with little interest in a Can system. Just as I had thought before