Can I use stereo amps with the KHE?
No! The KHE is designed for mono amps only.
Do i have to turn the amps off or stop playing before switching?
No. The KHE mutes the guitar signal before switching the amps.
Will it Hum or Buzz?
Most likely not. In case of unclean grounding or ground loops, the internal Ground Lift helps removing humm and buz.