Sheesh, the things the valve-heads put up with . The ASL's are imported from China so I'm not so sure that Mr. Lau is indeed the designer or simply sourced the product and is OEM'ing it. However I'd expect if he does post that he'd have more than a passing familiarity. It's an avenue. Well first Yogi, I'd confirm via email whether or not you're covered. Apart from that, I did a little digging and this is what I came up with as possible things to investigate that could be responsible for your hum. No guarantees...just possibilities. 1) Grounding issues: Confirm that all connections that go to ground do indeed so. 2) Defective phase inverter tube: Replace with one known to be good. 3) Defective capacitor: Generally people wind up replacing all of them (usually not that many) with polyester or polypropylene ones of a higher voltage rating. Not necessary to always replace precisely with the same capacitance...i.e. 0.047 is fine to replace a 0.050. There's got to be a Guitar Center near you. While a line attenuator may alleviate the symptoms, another approach is to pick up the Hum Eliminator (Made by Ebtech). It'll go between your amp and pre. Mr. Hamm had great success in using this to alleviate a hum from a different source. Guitar Center has an outstanding return policy, so if it doesn't work you should have no problem getting your money back.