I received the LTA Microzotil Preamplifier a few weeks ago after some significant preorder delays.
I can't compare it to the MZ2 since i only heard it once at the LTA office, but i have been baking it off against my Simaudio 430HAd, Pass HPA-1, and Massdrop CTH (with goldlion tube), and iFi Micro iDSD Black.
At this point i have only been listening with headphones; including mrspeakers aeon flow (open and closed), audioquest nightowl carbon, hd-650's, and hifiman he-400i's.
It probably won't come as any surprise that the Microzotil Preamp wins in just about every way over the Massdrop CTH... So i wont bother going into much detail there.
The iFi Micro is both a really good dac and headphone amp, one of the best values out there in my opinion... While the Microzotl Preamplifier does sound better, its not night-and-day better... But such is life in the high end.
Next up is the Simaudio. Now we are into statement level headphone amplifiers... I would describe the Simaudio as having power to drive anything, and no real sound signature of its own... If the source is good, the output will be good... If the source is bad, the output will be bad... I prefer the Microzotl Preamplifier.
Finally, the Pass HPA-1. Arguably this is the most tube sounding solid state headphone amp on the market. Accurate, plenty of power for most headphones, and it does just enough to make good recordings sound great, and bad recordings sound ok... I love this amp... The only issue i have with it is that it only has 2 inputs (3 would be nice).
The Microzotl effectively ties with the HPA-1 from a sound quality perspective for me. Arguably being one of the most solid state sounding tube amps out there (thats a good thing for me)... It does the same job of conveying emotion as the Pass amp... The LTA amp has a slight edge in the low end for me, but it's a bit artificial (boosted) - so if you love absolute neutrality, the Pass might be a better option...
Where the LTA amp wins for me in a big way is on usability. Lots of input options, and it even has a remote... It also wins on the "cool" factor with exposed tubes and great casework...
More to come.