I am going to buy Randall RG75DG3 or RANDALL RG-50 TC
I have few quessions about Randall RG75DG3.
andall RG75DG3 Guitar Combo, 75 Watt RMS, 1x12"Celestion Seventy 80, 2 channels w/3 modes, Gain 1: Classic hi-gain, Gain 2: Modern hi-gain, Clean channel w/boost option, Dual 3-band EQ's, 16-digital effects,12AT7 tube driven MOSFET power circuit, Effects loop w/level controls, Line out, RF4G3 foot controller included, 26,5kg

1) What does it mean RMS?
2) 12AT7 tube driven MOSFET power circuit - wdf is this?
Cann some explain it in simple words?