About USB screeches.
First, I have a Bifrost and I've never heard it do anything like that, but I can shed some light on the subject overall.
When you start and stop the data stream on a computer (which happens whenever you start or stop a track, and whenever you change the sample rate), you sometimes end up with what amounts to a little bit of bad data in the computer's buffer. When the new track starts, the computer "clears its throat" and dumps this bad data. The result is a really nasty burst of not quite white noise that sounds like a click or screech. Most DACs mute this, but sometimes a little bit manages to get by. (You have to pick a mute time: if it's too short then sometimes you hear a screech; if its too long, you bite off some of the music.) I've heard similar occasional screeches or clicks with quite a few different USB DACs. I suspect that you only hear it when the particular computer and software happens to send out a longer burst than usual, or the DAC gets "caught out" and doesn't mute like it should. Of the half dozen DACs I use often, three or four of them do it - at least occasionally......
