I just picked up a vintage Sunn 200s amp and 2x15 cab that sounds an looks excellent. My guess is that it is pre-1969 by the components, but can't be sure. Silver face, TK88 tubes...Head does have a slight buzz at high volumes near the front left side, but only when the amp is placed directly on the cab, and also only on certain notes that resonate more than others. My guess is the cab is so powerfull it may be causing a loose screw or something within the amp to buzz. The buzz is non-existant if the amp is not placed on the cab. I guess I could place some foam padding between the 2 to eliminate the buzz or have my tech open it up to clean things out and find the loose part, but I am hesitant to start futzing around with things. Any thoughts? Also, would you know where I could grab an operator's manual for future reference?