Hi Jennifer I just dealt with a similar issue, crackling coming from both speakers. Swapped out a bunch of tubes didn’t help. I started to think it sounded a bit like RFI. I had recently moved my modem/router to my listening/living room. I turned the modem off the crackling was gone. Moved the modem to a higher shelf problem solved. Another source of noise can be light switch dimmers. Can you share any more details on your setup?