I have connected Helix with four cable method to Mesa Single v2. Also I have connected 1xTRS+2xmono ( Y-cable) cabels into helix ext amp and Mesa Single Rectifier's rear pannel channel and solo. I can get the switching work but, then, Infernal buzzing and humming starts. I killed the humming with Behringer microhd hd400 but theres comming this electrical buzzing noise from inside the Mesa when swtiching the clean channel's "pushed" switch on!! Is the Helix even compatible with Mesa single rectifier when changing channels (ext amp) or am I doing something wrong? Thanks for advise.