The TwinSonic combines a clean boost (MORE!) and low-to-medium-gain overdrive (ROCK!)
The overdrive gives you the sound of your (non-master) amp cranked... at any volume. Therefore it is very neutral sounding by itself - it doesn't change the sonic or dynamic character of your setup.
Besides the Gain and Level controls, the TwinSonics overdrive section features two controls for precise fine-tuning. The TONE control affects the mids - turn it to the left for more lower mids and a fatter, softer tone or to the right for a punchy "in your face" sound with pronounced upper mids. The CUT control rolls of treble when turned clockwise (like in the old Vox amps).
The boost part of the TwinSonic provides a clean signal boost up to 20 dB. When used in conjunction with the overdrive, the signal can be boosted before the OD for more gain and sustain or after the OD for a volume boost or both at the same time!
Like the Diablo, the TwinSonic features the HEADROOM SWITCH for more dynamic range, more headroom and tighter bass in the HI position.