External DAC and a Processor with NO analog passthrough

I am using a Theta Casanova as my home theater processor. It does not have any analog passthrough. I would like to use a Wadia 27ix for my redbook cd's. My idea is to use an Adcom GFP-750 as the preamp for the the Left and Right channels. I'll connect the 27ix to the "CD In" on the preamp and the Theta's Left and Right output to the preamp as well. The preamp would then passthrough both of the signals (untouched/uncolored according to Stereophile) to the amp. I could use the same front speakers and amp for both the 27ix and Theta this way. Has anyone ever done this? I am guessing the Wadia output signal, the CD In on the Adcom and the Theta's Left and Right channel output are all the same type? Anyone?