Rfjaudio,
I too have an Anthem AVM 20 and run the front left and right interconnects through my Rowland preamp via the unity gain passthrough and out to my Classe' monoblocs. If your pre-amp has that capability do it that way.
That being said, you certainly can hook up the tube pre-amp to the RCA inputs on the power amp. Just use one source of input at a time into the power amp.
I too have an Anthem AVM 20 and run the front left and right interconnects through my Rowland preamp via the unity gain passthrough and out to my Classe' monoblocs. If your pre-amp has that capability do it that way.
That being said, you certainly can hook up the tube pre-amp to the RCA inputs on the power amp. Just use one source of input at a time into the power amp.