I'm guessing "MG" is "Medium Gain", and "HG" is "High Gain".
Klon is likely a Klon boost pedal in front of the amp.
HTH
That's true.
LG is Low gain
MG is Medium gain
HG is High gain
The rigs with Klon use the Klon KTR as booster
The rigs with SD9 use the Maxon SD9 as boost/distortion
The rigs with Fuzz use the Guitar System Fuzz Tool
All rigs are profiled using the Universal Audio API Vision channel strip/preamp as plugin