OK, just got back from my visit to LTA. As most of you know, the staff are among the kindest and most accommodating in the business. Very grateful to LTA!
I brought my RME ADI2 DAC, my ZMF VO Ltd, and my laptop with lossless audio files. My goal was to really take a critical listen to the MZ2 and MZ3 and I had the luxury of being able to A/B/A/B them, listening to the same music that I had pre-selected and determined to be sufficient to put each amp through the paces.
I may go into much further detail, when I have more time to type and reflect, but listening to the MZ2 first was great. I listened to about 12 songs and truly loved what I was hearing. Very strong and balanced, and impressively good separation and staging. Then I plugged into the MZ3 and it nearly brought tears to my eyes (very close, as music can be quite the visceral experience, if certain songs have personal meaning to you). Well, after listening to a few tracks on the MZ3 and going back and forth with the MZ2, it was game over for me. The MZ3 is now a must-have.
The detail in the MZ3 upper-midrange and highs are really captivating. The distinction and clarity, crispness, and detail in percussion and strings was incredible. The bass was very tight and yet quite present and (again) visceral to experience. My ears can absolutely, undoubtedly, and clearly tell the difference between the two units (both powered with the LPS+). If I had never heard the MZ3, the MZ2 would be completely satisfying. I did not intend to entertain the MZ3, due to pricing, but now I'm completely sold. I'm going to likely wait, save a bit, and buy one in the coming months. Not that I've had tons of exposure to all the high end headphone amps out there, but this is hands-down the best I've ever heard. This will be an endgame level purchase.