Hello khenegar, I've been watching this thread as a Summit owner, these are somewhat new speakers so panel issues should be minimal (abuse like heavy smoking, flinging of hot oils during sex while listening to Bach...etc...etc notwithstanding). You vacuumed them and took care of them. switched panels and it is the panel with the issue.
My old Sequels used to make that same noise when no music was playing however, they still sounded wonderful, it annoyed me! They were so old the sereal #'s aren't on the website. If you aren't hearing any sonic distortion and you don't plan on selling them soon, no worrys mate!
