The only popping i have ever encountered on my Roadking happens between channel 3 (on vintage) and channel 4 (on modern) if either channel is on a different setting it will not pop.
Also on top of this it only pops when I go from ch4 to ch3, and only then.
Any changes in my switching or my channel setup and it doesn't pop. Its so specific i never noticed it in the shop nor when i got it home for a while either.
Although it doesn't bother me in the slightest anyway cause once the amps up to normal levels its barely audible.
Before I bought mine, I read (on this board) that if you didn't cycle through the channels before you turned it off standby, it could pop. So I do, and it doesn't.
old joke:
man: Doctor, it hurts when I do this.
doctor: Don't do that.
I cycle through the channels once, and it doesn't happen after that. IMHO it is a non-issue. When I play live, I just make sure to run the amp through its paces at sound check. Once I do that, it never pops.
Mine does it too and I am running mine through a power conditioner. Like the others, once I cycle through the channels it is barely noticable. I also cycle through the channels before I take it off of standby.