Thank you vey much for your reply. I think I phrased my question improperly. I understand that is does not directly process the signal. A pedal 2 input jack is not an effects send and return, I am clear on that. What I am unclear on is whether the pedal attached to the PD HD500X needs to be active (powered), or if a passive (umpowered) pedal will suffice to modulate the signal.
Can I use a passive (No power requires) pedal such as a M-Audio EX-P Universal Expression Controller Pedal
or
Do I need an active (Power required) pedal such as a Effect Pedal Electro-Harmonix Single Expression
Thank you for your patience with my newbieness.