Hey guys, my 'used to be' intermittent problem with this Combo just turned permanent. It has happened maybe 1-2 times in the past 2 years, for a couple of hours .. then went away. The amp makes a strong background noise, sort of like a distorted ringing .. don't know. The sound of the bass does come through, and doesn't seem very distorted. (of course, ringing/noise is still there). This happens indifferent of whether a bass is plugged in or not. Gain / Master Knobs (or any other ones) don't influence the level of the 'noise' I've uploaded a video (Tweeter is disconnected, as i first thought it was on it's way out. With tweeter on, noise is only louder) with the sounds its been making. Please have a look and let me know if the issue is familiar or something .. Thanks for the help!