Just got the HX Effects today after wanting it since it came out because it would be nice and easy to switch between sounds and the extra effects are a definite plus. So, after setting it up in the 4 cable method as described in the manual, I set up a basic patch with delay, reverb, and overdrive. I set things up so that delay and reverb would route through the effects loop and the overdrive would go through the front of the amp. So far, so good. I then wanted to add external switching to change channels on my Mesa Mini-Rectifier head. Got it all set up and it works but there's a hitch...Every time I switch on the dirty channel on the amp, I get a pop. I've tried different cables, the one that came with the amp and that works fine with the amp's footswitch, a TRS cable, and a standard instrument cable. No changes. It still pops. If I run the HX through the front of the amp it works just fine, no pops. But, who really wants to run delay and reverb through the front of a high gain amp? I've even turned the effects loop off while running through the effects loop and no pops. I'm stumped. I've done lots of google searching and there are no solutions it seems. Am I doing something wrong or is the annoying popping just the way it is with the HX and my Mesa? Any help would be appreciated. Thanks.