My Click-Less Looper is popping when I turn ON a particular Loop, what do I do?

We actually get this question quite often and it's always been the same answer. Popping sounds actually come from pedals (specially overdrives and distortions) that have capacitors that leak DC+ into the audio lines. This problem has nothing to do with the looper, as inside the looper there is no such capacitors or any other active components in the audio pads. 

One way to test that is not the loper, is to identify the loop that might be causing the problem, then plug a cable to the SND and RTN jacks and then turn that loop ON and OFF, did it pop? if the results were negative, then you have pedal that leaks DC+ into the audio lines not a bad looper.

Furthermore, the more gain you use from a pedal, the higher the "pop" and noise will be. If try that pedal set to a very high gain, and connect it directly to the amp you will see the pop that it causes. This is absolutely normal and expected from such pedals. The looper acts as a gatekeeper for that same pedal, so if the pedals pops connected direct to the amp, it will also pop when is connected to the looper.

For further reading, please see link below on why this popping happens on some pedals. 
http://www.geofex.com/Article_Folders/box_pop.htm

Please also read what Robert Keeley, from Keeley electronics has to say about that bellow

"As with all true-bypass effects, switching is not perfectly silent. There may be some popping sound when you switch. To minimize this, leave the effect you want to make true bypass ON, then switch the Looper footswitch 4-5 times to discharge any DC voltages. Running several effects or certain types of effects may make the popping louder or quieter depending on their design. A popping sound is not an indication that the looper is defective or not working. It is the small drawback to the great improvement in tone that takes place when poorly buffered effects are taken out of the loop (thus made true-bypass)."