sa9023+cs4398 usb dac channel cuts off

[auriga2001in]

I have a usb dac board (using the SA9023 and CS4398) which works fine for most part. Occasionally the left channel cuts off, and there is only hiss in the left channel. The recourse is to restart the DAC (power cycle).
What could be the issue?
Thanks

 

[Markw4]

Could be a ground loop getting electrical noise into the circuitry. Ground path would be through the USB connector ground and the analog output grounds.