Auto Filter offers a variety of filter types including lowpass, highpass, bandpass, notch, and a special Morph filter.
Although Gain and Volume work together to determine Amp’s overall level, Gain is the primary control for the distortion amount.
The SMP circuit is a custom design not based on any particular hardware.
It shares characteristics of both the MS2 and PRD circuits and is available for the lowpass and highpass filters.
For example, increasing EQ levels can, in some cases, also increase the amount of distortion.
Presence is an additional tone control for mid/high frequencies in the power amp stage.