Well, this is a new one for me: the iFi iDSD micro FIRMWARE was causing my PC to crash, big time! After a Windows 10 update in Feb, 2020, my PC would not boot properly. It would sometimes take well over 15 minutes, replete with BSODs, auto-restarts, failed (and successful) auto-repairs (multiple per start-up), and even necessitating CMOS BIOS resets to factory defaults. This went on for a couple of months and I was about to re-install Windows when I'd come across an error code on my ASRock motherboard's 2 digit display indicating a USB fault. It had thrown numerous codes before but before this one. I've had my Black Label hooked up almost continuously; it's my main DAC now, and unplugging it solved the problem instantly. I'm back to 15 second start-ups.
I had previously updated the firmware to one of the MQA versions (I don't remember seeing any warning against doing so back when I'd done it) and all had worked well until that Win 10 update. Reverting back to 5.2A solved it all, and boot-up is just fine with the iDSD plugged in and powered up. I'd searched here at Head-Fi but didn't see any reports of this, hence this post. Maybe iFi had added the 5.2A warning in response to this issue? Anyway, if any of you are experiencing such issues, give this a try. It's just as well, for I never used MQA anyway.