This is driving me nuts. I use an Orange TB and Sp212 so have a half size rack which holds my in ears, my Boss TU-50 tuner and Sennheiser Freeport wireless. I have suddenly developed a buzz. I have so far swapped all patch leads, completely replaced all the 3 parts of the wireless (body pack/lead/transceiver) plus checked all plus earths. Still the buzz keeps coming back. Stupidly, sometimes stops if I move the rack. I am starting to think that maybe the tuner is the issue. I am gonna take it out of the link on Saturday and see if there is a difference. I thought these things were bomb proof. Any thoughts? dunno if any local tech would be able to look at the tuner to try fix. Perplexed!!!