Resistor on back panel of ACA -- quick question

Curious: what is the consequence of not attaching the 39K resistor between the RCA and the back panel switch? I appear to have lost that resistor. I can order another, obviously, but given the backups at Digikey who knows when it will arrive. Just would like to know if I need to chase that part or can just leave it out.

I plan to run mono blocks if that makes a difference to my situation.

Bonesthrower
Lincoln, Nebraska