Cerrot, I purchased my UX-3 used, but I'm reasonably certain the unit had not been played very many hours (mfg date was just 3 months from the date I received it). My starting point with the UX-3 is therefore somewhat unknown, but this is what I found: upon first listen I was a little worried that it would be too "digital" sounding. It didn't sound as "smooth" as my previous APL3910, but it was more dynamic and detailed.
After a week of non stop play, it became significantly "smoother", but still the strengths of the player were evident...dynamics, detail, and impact. Over the next few weeks, the player became "balanced". By this I mean, the strengths of the player were clearly the same BUT, the player "opened up" in a way that helped transport me to the event. High frequencies were no longer spot-lit, but contributed to putting in context the venue of the recording and filling out the overtones of the instruments in a more natural way. I was very happy with the player at this point, but wondered what was possible, given the obvious strengths of the player.
I then sent my UX-3 to Steve Huntley of GNSC and he spent a great deal of time performing a Statement mod to the player. This mod involved the addition of a great many Black Gate caps in the power supply section as well as many other passive part upgrades and power supply filtering. When I got it back, it was clearly a half step back from when I sent it out. Over the next few weeks of constant play, it opened up in such a natural way...much better than before. The strengths no longer stand out, it's extremely well balanced and serves to bring me to the event. This is not to say that it is not dynamic and detailed...it is...it's just always in support of the music, not something of its own.
Bad sounding CD's still sound bad, but the difference is that they are listenable AND I can tell why. Different spaces, mic placement, mixing and mastering decisions are much more easily discerned. To me, particularly with the UX-3, the burn in process is a balancing process.
The dynamic and low-level detail capabilities of the UX-3 allow for a more involving listening session. In particular, the micro dynamic capabilities, combined with the detail retrieval allow me to get alot closer to what a musician is doing. They are not, however, something by themselves...dynamics and detail are present in such a way as the sound is more believable, not "impressive" if you understand what I mean?
To me, these qualities are an essential platform to get closer to the music. It must be balanced though...the highs have to open up and they do with time. If your system tends to emphasize some of the stronger qualities of the Esoteric though, you could lose the balance.
Good luck!
Jordan