Speakers pop when volume knob is turned


I have a MF A300 connected to a pair of Thiel 1.5s. The amp is also connected to a REL subwoofer via its high level Neutrik Speakon cable. Problem is, and this has just developed, my speakers "pop" or "crackle" when the volume knob is turned--no music playing, just the turning the knob. Is this normal? I never heard it before. Should I just play ignorant and just not turn the knob without music. Or is the pop indictitive of some impending failure in the amp?
calbrs03
Thanks Pmotz. The situation has worsened, unfortunately--it no longer pops, it tears. Must be one dirty potentiometer. I shut down the system and will take the amp in for service.
You probably have a dirty volume potentiometer. A proper cleaning would fix it, but I would not attempt that yourself unless you know what you are doing. Some cleaners can dissolve plastic! A temprorary solution would be to spin the pot back and forth a few times with the power off of course. The crackling could damage a tweeter if it is severe enough so either get it fixed or be very careful when changing volume.