I'm interested that you enjoy this with the Fostex. I have a pair of ZMF vibro mk 2's inbound in probably a couple of weeks and I will be trying them with the MAD and the Woo. I have run my HD600's with the MAD, sounds very good, but its probably a toss up with the WA6SE. With the Grado's, absolutely no contest!!!
I've heard good things about the ZMF stuff. I've never heard any, although I'm interested in the ZMF Omni's. I like, but don't love the LCD-2's on the WA6SE. I feel the same way about the HD-600's on the MAD amp. The Fostex is more fun by far than the HD-600's with the MAD amp.
I see you've run the T1 and HE-400's as well. I've heard HE-400's sound great on the WA6SE (under meet conditions). Did you try either with the MAD amp?
My LCD-2's (gen.1) sound really quite nice with the MAD amp for non-bass heavy classical music, which is a primary use for me.