[PROBLEM] Tics when playing high-resolution PCM files

[DRONE7]

Hello,
when I play hires PCM files
I hear occasional but very annoying "tics".
It happens with some 24/96, 192 and 352 Khz flacs.
On 352 flacs they are more frequent.

I suspect the issue is due USB lags
on external HD, or on USB dac.
I have Moode 8.1.2 64 bit on RB 3B+, connected to a topping DX5 usb dac
and external USB 1 TB 3.5 disk.

no errors in moode.log

Is your external USB 1 TB 3.5 disk self powered or is it powered by the Pi' ?
If the latter then you may be overtaxing the power supply of the Pi....and exceeding the USB current capability.
This would be probable given that the files play fine from the SD card as you've reported.

You could try some files from a USb stick instead of the hard drive as another troubleshooting test.