It's on one of these I thought this was a (pretty bad) grounding/shielding issue at first, when I was using my Hartke A25. Then I switched to my Peavey Basic 40 (dorm room) and there's no buzz at all. It buzzed a bit on my Carvin BX600, but not like on the Hartke. What's going on? I'm thinking maybe it's because the Basic 40 has a two prong plug, but I'm not sure and don't know much about things like that. My knowledge of electronics is limited to simple DC circuits.