People generally say that it takes about 300 hours of so to break in. I've had one in my system for close to a year now and I really love the sound of it. It did sound a little digital originally, but after a long period of break in, it did open up a bit and sound a lot less digital. I have mine with a bridge and I think is sounds extremely clean, natural, and almost analogue-like at time. I prefer it as a source over my VPI Scoutmaster.
The other great thing about this DAC is that you can bypass all the stupid Async USB BS that is going around with all new Dacs that came out this past year. There is also too much fussnig with computer audio as of right now...computer type, hard drive type (ssd vs hdd), async usb implementations, software players (amarra, pure music), and quality usb / coax cable all make it waaaay too fussy for my likings with too much tinkering. With the Bridge, you can bypass all that stuff and just enjoy the music, knowing that it's feeding the DAC properly.
X2 on the Bridge. I can tell the difference between 320 and lossless easily, I'm not sure any other DAC in this price range can compare. I tried the Sonic Frontier DAC but did not like it as much.
I think I can't tell the difference after 200 hours of burn in. PWD match very well with tube amp, it match WA22 better than Phoneix or M3.