Input A comes with a recessed function switch. This is ideal for instruments that feature piezo transducers. By selecting this input into the outward position you'll find that it also particularly suits bass instruments that have both passive and active pick-ups. Should you switch the input inward then this increases the Independence from 220k to 10meg Ohms. Watch out though! This also comes with a 10dB boost. You should engage this if you feel the transient peaks of a piezo pick-up are excessive and need smoothing out.
Input B comes with drag control. This is incredible for emulating the "pure" tone of plugging your bass guitar directly into an amplifier without any buffers to colour the signal path.
