You can find more info on page 141 of the dLive Firmware Reference Guide. From that page:
Mode selects the model, there are 5 available.
Mode A Triode Valve Preamp Model. Rich in second and third harmonics. This model is
the cleanest available on Saturator with low harmonic distortion and a gentle roll-off on
frequencies over 10kHz. (Least aggressive).
Mode B Pentode Valve Preamp Model. Rich in second, third and higher order
harmonics. Minimal high frequency roll off.
Mode C Late 1960s germanium transistor based Preamp Model. With characteristic roll
off on frequencies over 12kHz.
Mode D Channel strip model with vintage bipolar transistor and small signal transistor.
Wide high frequency lift at around 8kHz and for air and clarity.
Mode E Tape Drive Preamp model. Accurate low and low-mid attenuation with extremely
aggressive levels of distortion when Gain is turned up to maximum. (Most aggressive).
.
