Unfortunately this popping is a known issue to Line 6. It is a major defect, and it is why I returned my SV Mark II 112 combo. In my case, I often change patches during songs which means you would hear a loud pop. This is ridiculous. Line 6's solution to people is to turn you patch volumes up past 12 o'clock to lessen the pop. However, this means my master volume was just way too touchy going from no volume to ear-bleeding volume. Line 6 really should fix this problem, but Spider Valve sales are way down so maybe they are not putting any resources to making SV improvements/fixes. Guitar Center told me they are not going to carry them anymore. My local Sam Ash stopped carrying them, and my other local Atlanta dealer (Ken Stanton) no longer carries SV amps. They also said their sales on Spider IV amps are way down... that the Fender Mustang amps are far out-selling Spiders. Although I love the SV concept and its flexibility, I have moved on from Line 6. Just too many problems, too much tinkering and too much tweaking required with their products. All that said, I should say that I bought a SV 112 Mark I version when they first came out... about 2007. I still have it and I have never had any problems with it, and it does not have the popping issue like the Mark II version. However, I just can't take anymore of the digital fizzy sound on the overdrive/distortion models. My wife says it just sounds awful compared to my other amps.
