I think Rob or Bruce would know better, but I THINK it just a switch on the faceplate that allows single channel user to select channel A or B. it Is non-footswitchable.
I'm pretty sure the switch allows you to choose which of the module's two channels is active when you switch to it. On his earlier two-channel modules, channel A would always be the active one (or, if you made a change to the circuit, channel B).
I can speak for the switch I offer, which is probably similar to what Bruce did as well. The switch allows Randall amp users to have access to both channel A & B when used in a non-Egnater amp. You are not able to foot switch to both channels (the Egnater amps use a different MIDI switching system to provide for that), but you can select the module as you would any single channel module. The switch setting dictates which channel you are using when the module is active.
