Yeah, stay well clear of Audiophool
credit card surge and brownout ~power conditioners~
and the jargon slinging salestards who would sell their family for a high commission, much less have second thoughts burning your wallet
If it's not a heavy weight Sola, Eaton or similar ferro-resonant job, or online sine wave UPS,
don't blow your money and prayers on a lightshow equipped placebo-conditioner
besides the great suggestions above, I would first go through every single power cable, IEC lead, power board etc etc for correct polarity
then check the incoming power sockets, and check that the mains is wired correctly and screws to the breakers etc secure, firm and tight >
wearing gloves, rubber boots, glasses, and with the mains breaker OFF of course I would open up the test gear too and ensure they are wired properly and no factory or backyarder tech repair stuffups
Yes, it's time consuming and may be an exercise in futilty,
but ONE crap cable, poor or reversed connection somewhere in the works can drive you nuts FOREVER...
and send you to the poor house throwing money at the 'problem/s'