Unloaded amp output

I use a Proceed HPA-3 for LCR, but I've discovered the KEF Reference 107/2s image so well I prefer the sound without a center channel so removed the speaker. Long ago, Madrigal told me Proceed amps were stable even without a load, still I wonder if I should use a 4Ω resister across the center channel. Any advice would be appreciated.

db