Well I had the L3k's some time ago. I tried them w/ the EMP AE, the Rudi RP6, it's matching amp (forgot the name), SDS-XLR, MPX3 (maxxed).
It sounded the best out of the MPX3 actually (to me). But I couldn't get used to the complete LACK of air, and what I feel ARE rolled off high's. It had a very, umm, "intimate" sound I guess you could say. It even has/had an upper midrange spike around 1-3khz (which came off as harsh or rolled up). Certain recordings sounded good, but in general, it did NOT have the tonality I usually like...
...Nevertheless there was something about these headphones that kept me listening. It was a unique and intriguing way to listen to my music. Eventually I ended up trying to EQ these suckers. I even put up a thread on headfi somewhere. It was interesting, and I was able to isolate and find just those frequencies I thought needed some work. The headphone sounded better (in that it now sounded less like an L3K!), but it also sounded more sterile, and less effortless in its reproduction. The bottom line was, I realized I was asking something out of those phones (and those drivers) that it clearly wasn't designed to do. Hearing the rest of the AT line, I guess, to some degree, I'm not an AT Fan. Eventually I ended up selling them.
BUT, nevertheless again, there is something about these phones that still, to this day, intrigues me, and I woundn't be surprised if one day I acquired another pair.
Neil