I am just wondering why you are using HDD for playback? I have a uTrack here too that I use for playback (24ch/48kHz songs) and I solely use USB flashdrives.
In the 10-somehting shows I did, that has worked flawlessly for. I am using an expensive 128gB Kensington, though some cheapo 64gB TDK seems to do the job just a well.
No moving parts, no issues so far.
I also tried to record on these babies once, but then the uTrack indeed starts to complain not being able to record 48khz/24bit, and that all makes sense to me. Though as read speeds are mostly faster than write speeds on flash memory, the playback works very well for me so far.
So therefore I was wondering why you bother going the HDD route?