Hey-Hey!!!,
being a one-source builder sort of simplifies tha one for me...If you put the switch right next to the inputs, you can run a single wire to the volume knob. If this changes the amount of noise pick up, I am not sure.
I'd consider the neatness and simpler is probably the better way to go. Short wire to teh switch, single to the volume control. That's my opinion anyway.
regards,
Douglas