Krell 4K UHD Processor: Troubles Setting Up Phantom Center Channel

I recently purchased a used Krell 4K UHD Foundation Processor. However, I have been unsuccessful setting up a phantom center channel. My front speakers are Wilson Watt Puppy 7s and they image super well, so I’ve never really wanted or needed a center channel. With my old Showcase Processor, I simply set the center channel to None and the signal was sent to the L/R channels, no problem. I did the same with the Foundation without success. I’ve tried various other settings in the menu with the same result - no sound from the center channel unless I wire the processor output to an amp and speakers. Anyone else have this issue or any guidance on a fix?