There's certainly an input cap that be changed (
not removed!), but that's unlikely to make a difference since as you note, the actual phasing is done digitally. The obvious solution is to add a simple clean blend like
this. I'd also add a simple RC tone control on the clean side since you likely just want the clean lows to pass through and not your entire clean signal.
As for the expression pedal, it just duplicates the rate knob. So you can hear what this sounds like by left-hand tapping out some notes while tweaking the rate knob.
