Hey Guys, I literally just picked up a clean 1001RBII from the classifieds here two days ago. The entire transaction was superb and I would happily do business with the seller/trader again. After experimenting with some different sounds, I figured I would revisit the GK sound after selling a 700RBII just a few months ago. The amp arrived perfectly packaged. When the UPS delivery driver dropped it off, the amp inside did not move or rattle inside of the packaging box. Shortly after, I plugged everything up and the GK sound was once again knocking books off of the nearby shelves HOWEVER, shortly after (and I mean 10 minutes after) the amp started to loose significant amounts of volume and began to distort (almost like a low saturated tube type of distortion, but not defined or clear) The amp was NEVER pushed to a crazy volume in my possession. It also began to create very unusual "filter like effects" and it felt like it was increasing volume, and then decreasing at the same time. This entire episode was going on for about thirty minutes until suddenly it stopped, and returned to normal, just like that! This same situation has been going on for the last day or two now. There has been times where it has worked flawlessly for a long period of time, and then there has been times where the distorted sound would prolong for longer and longer periods of time. Presently, it works fine and has been for the past hour or so. My setup for this specific rig is: An Avatar B210 Neo (500 Watts at 4Ohms) (Again, it is not being pushed hard) A Ernie Ball Music Man Sterling And the GK 1001RBII.. I have tried different cables, batteries in the Sterling, Speakon to 1/4'' adapters, different speaker cables in general, you name it, I tried it, without opening up the amp because that is something I don't really want to do at the moment. I know most of you might say bring it to a tech, but before I look around for one (my current tech is not available for a few weeks) I figured I would post it here. Thanks for all of your responses and input!