My RKII pops once when coming out of standby, after performing the "standby shuffle". It pops only when going from Channels 1,2 or 4 to channel 3.
Serial effects loop... I'm not sure what you trying to say (still waking up :evil Anyways when I move my send level knob the volume goes up and down. I still have control of my other volumes (masters/output).
You don't always hear the "popping" noise if you switch channels, and you can eliminate it entirely by cycling through the channels a few times before you take the amp off "Standby".
I'm not quite sure what you're asking on the second question...could you elaborate?