How's your equipment exactly connected? Buzzing from the speakers usually indicates a ground loop somewhere, and if you are not star-grounding, a good power distribution center should help; also assert that you have a good ground connection everywhere. I would not exclude a faulty piece of equipment either. Personally, I would move methodically, first by unplugging everything, then starting with plugging in and powering on just the amps (no I/C cables connected) connected to the speakers, and move up from there - at some point you should be able to find out what's introducing the buzzing. Did you also report transformer buzzing in the past, or am I not remembering correctly? If so, is this the same issue? I did have buzzing from the speakers at some point in the past, and traced it to a bad ground connection of the power cord to the preamp, due to the cord's weight. As it turns out, the female EIC connectors used by Shunyata are not large enough for the equivalent Spectral input male EIC's, so I now wrap all of them with a couple of rounds of electrical tape, for a tight and firm fit into the hole. The nut that I am, I actually opened up all components and asserted continuity and very low impedance between the cord's male ground prong and the ground wire behind the IEC plug within each component; careful if you decide to do the same.