The good news is that both channels work.
I did switch the Amp Modules per suggestion of an acquaintance on another site. The Sine Whistle that I reported did follow that module.
The module that was not receiving input yesterday...
...is doing the same thing except it is persistent where the other module does become inaudible.
I'll say this... I can still hear pretty high frequencies.
I'll reach out to Hypex tonight and see if there is anything they can tell me to help troubleshoot this... Or if they are both likely bad modules.