Before you do anything else: Next time you hear the crackle, tap each of the tubes in that channel with the eraser end of a pencil. It the sound gets worse, or disappears- you've found your culprit. Start with the driver/phase splitter tubes, as those usually generate that type of sound when faulty.
Crackling coming from Right Speaker - Help
I recently began my journey into the world of tube amplification. I purchased a Genesis I60 on audiogon, and have been extremely pleased with the sound. I moved from a floorstander (Legacy) to a monitor (Focal 906). In the past month or so I have heard a crackling sound through the right channel periodically. It has been present with both sets of speakers. Being a bit of a novice, I am not sure if this is an issue with an aging tube, a cable issue, etc. Any help or guidance would be greatly appreciated!