I've had mine for a bit over a month now. It truly has continued to improve over this entire time. Seems like the process has been lots of increasingly good listening session, interrupted by some harsh sessions. But the overall arc is toward increasing effortlessness and ease. The coolest aspect has been increasing emergence of a kind of natural layered texture that good analogue will give you, but has often been elusive with digital.
Recordings that I used to think were unlistenable are now listenable, even engaging. They're still not great recordings, but they don't hurt my ears.
Guess what I'm saying is that you should hear a definite improvement during the 15 day audition period, especially if you keep it playing. But there's even more improvement after that. Keep us up to date on your own impressions.
Oh, one more thing. My experience is that good DAC's are very sensitive to what's upstream. Audirvana and Pure Music have put out new versions this past week. Very noticeable improvements in SQ.