I have a May KTE DAC connected via USB and I2S and have never heard a delay on either input.
Mine is connected to a Holo Audio Bliss KTE HP amp and the combo needs about an hour of playing time (I’m not listening during this time) before it sounds it’s best. Makes more sense for it to be the amp that needs this time but I’ve noticed the May gets warmer than the Bliss. Not the PS chassis, it stays cool, but the DAC chassis itself. So it could very well be the DAC that needs the time. Not a big deal, just kind of surprising to me. My previous tube amp only needed about half that time, though it was used with another DAC.
It is an outstanding DAC, though. Endgame for me. I’ve had a PS Audio DirectStream Mk1 and a Yggdrasil LiM and the May is the cream of the crop, and I really liked both of those previous DACs. In fact, the Yggy is probably the best value as it’s performance exceeds it’s price. No I2S input though if that’s something you want (I did). The ability to switch from over-sampling to non on the May is a very cool feature to have. I leave it in NOS most of the time but there are recordings that benefit from over-sampling.