Audio bitrate is not constant on new Pi

Hi there,

I recently upgrade my setup from a Pi 3B to a Pi 4B. My music collection is on a USB pen drive and output is via a Cyrus Soundkey DAC.

On the Pi 3B, I never used to have any audio issues, but since upgrading, the audio output goes strange about once a minute. It sounds like the bit rate is “crushed” and then after a few seconds, it fixes itself.

It’s a fresh install of Volumio, Please can you suggest what I can tweak to solve the issue?