I've built a couple of OTL amps => you're always fighting with the problem of tapping power directly off the output tubes. The usual solution is to parallel a lot of tubes, which reduces the output impedence and increases power, but at the cost of a lot more complexity and an increased need to have well-balanced tubes. I use a pair of Atma-Sphere M60 amps using a Circlotron fully differential topology and they are fantastic for higher-impedence speakers. They do not do well at all with speakers that drop impedence at different points in the frequency curve.
Nevertheless, getting rid of the output transformers yields a huge improvement in clarity and immediacy -- much more of the "you are there" feeling. One amp that is sort-of OTL-ish is the David Berning MicroZOTL 2.0, which delivers plenty of power for my LCD-2's under meet conditions (using music I didn't know). That might be something to consider if you're looking to go the planar route.
OTOH, if you're looking for a nice complement to the Senns, you might try the high-value Fostex X00's from MassDrop. At $400, you save a bunch of money, and they are the cat's meow for electronica, EDM, and rock & roll when used with the MAD amp. The Senns walk all over them for balance, especially for classical music, but the Fostex cans are a whole lot of fun. And there's always Grados, which are the perennial recommendation for MAD amps, for good reason. I have used and abandoned several Grados: each was a nice match but none of them were comfortable enough for me and my long listening sessions.
I routinely use my LCD-2's with my MAD amp, and they are really not a great pairing if you like to crank the volume. Mostly I'm listening to small-scale blues, classical quintets, that kind of thing, and I like the sound a lot, but I don't recommend Audeze's for use with the MAD. If the output impedence s actually 2 ohms, the 32-75 ohms of the Audeze's will be well-damped, but the MAD doesn't deliver enough current to help them sound their best.
Hope this is the kind of feedback that you find helpful.