Unused third channel

I have Proceed HPA 2 and 3 amps. I use the HPA 3 for LCR, but the KEF Reference 107/2s image so well I find that I prefer the sound with just LR and have removed the center channel speaker. Long ago, Madrigal told me Proceed amps are staple even without load. Still I wonder if I should use a resistor for the center channel.

Why not use the HPA 2 for your main speakers? It would be a much cleaner solution than fooling with a resistor.
you can use unused channel terminals for electric massage during listening :-) that will take care of load.