Skipping during playback (Volumio 2.853 on RaspberryPi 3B + HiFiBerry Amp2)

Hello - I am having some issues with music playback and would appreciate any suggestions to fix.

I am running Volumio 2.853 on RaspberryPi 3B, with HiFiBerry Amp2 as DAC.
Music is in FLAC format and is stored on a SSD connected via USB.

During playback, the first few tracks (maybe 10 minutes) will play fine. After that point, playback is interrupted by a “skip” or “pop” that lasts approx 5 seconds (I hear a “pop” and then no music for 5 to 10 seconds). Once this starts happening, the popping will reoccur every minute or so. If I pause the playback for several minutes, the popping will stop, but then resumes after a few more minutes.

I would guess this to be a buffering problem. I have Volumio set with maximum buffer (12mb/40%). Changing these values does not help.

Following recommendations in other posts, I have changed DAC model in Volumio setup to “HiFiBerry DAC Plus”. No change. The popping/skipping continues.

Any suggestions? Thank you in advance.