VRM is a Voltage Regulation Module, Trinity's form of a type of power scaling. It is VERY useful for getting the sound of the amp at lower volumes and an 18 watt can be loud
The boost switch is just what the name implies, boosts the signal through the (on my SIIIv6) TMB channel. Similar to a boost pedal in concept.
All of the kits and amps have a selectable speaker impedance knob so that you can, on the sIII variations, choose between 4, 8 and 16 ohm speaker cabinets.
I believe that the master volume works only on the TMB channel. (it's no longer called that on the latest documentation, the TMB Volume is actually pre-amp gain and the Master Volume is now just Volume. This descibes how the controls work with the amp topology).
The two channels can be jumpered on the sIII's and this adds flexibility to dialing in the tone you're looking for
The SIIIv6 that I built has the selectable speaker impedance knob (standard), the boost switch (optional) and the VRM (optional) all on it.
Hope this helps
Oh, and I never soldered ANYTHING (except copper water pipe) before building my first sIII and it worked
![Very Happy :D](./images/smilies/icon_biggrin.gif)