One of my clients hvx200 seems to record intermittent low buzzing. I am sending a line level out from my 442 to line level into the hvx200 - settings are set to manual as we always do. My return audio from camera has the low level buzzing and when recording to p2 it is identical.
They have two hvx200's and a hpx500. Never had any issues with buzzing on the other hvx200 and hpx 500 with the exception of the phantom beeping when recording to p2 cards which is a separate issue.

This low level buzz is not interference from power or any transformer that is around.

Has any one had this issue before?

Could the pre-amps in the hvx200 be going bad?

schoeps cmc641 to sd 442 line level out to line level in hvx200.

Thanks in advance for chiming in .

did you try swapping xlr cables? check shield connections and grounds in the connectors - most likely the source of hum.