I recently acquired a Mark V and it is awesome. I am using it with my Helix Effects unit, using the external amp switching feature . I am using a 4 cable method to separate effects between the front and FX loop. It works really well and allows for great control from the Helix for song-based patches. However, it does cause a really loud hum which is really noticeable on channel 3. Has anyone else encountered this issue or have any ideas what might be causing it? If I remove the cables from the channel 2 and 3 ports on the back of the amp and just use the boogie switch then the humming stops (the Helix is still plugged in for effects). I think Ive tried all possible switches on both the Mark v and the Helix but can't seem to eliminate it (even a noise gate after the effects loop doesn't completely remove it and of course that clamps down on my tone)
Thanks in advance!
