#1
Does anyone know if you can still use the head on it's 30 watt mode with the cab that comes with it? Or what setting the cab has to be on?

This is the back of the cab
#3
the 30w mode just reduces the volume.
it can be done. switching from 100 to 30 wont hurt anything
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Rig:

Charvel San Dimas Style 2 Pagan Gold
Traynor YCS50
Visual Sound H2O
Morley Bad Horsie
Ibanez TS9
ISP Decimator
EHX Metal Muff