Could you please what is the source connected to the inputs?
Are you using balanced connection?
I made tests with both machines and disconnected everything (so the device should only record silence)
Could you please do the same test but connect something to the inputs. I mean to have some load on inputs.
What about the input levels during the recording? Are the levels big enough? I mean the uTrack24 has SNR A-weighted > 100dB with +20dBu input level, if you have much lower level to feed the inputs the SNR can be worse.
Do you have a chance to test with external powered USB drive?