Precisely matching two pre-amp inputs

Hey Swamp - I know I’m missing the obvious here … :blush: … how do I get the test tone from the CD to the physical input of the pre-amp? It’s a .wav file, or some such digital thing, on the CD … how do I get it out of the digital realm to run through a T/S cable into my preamps?

I feel like such a dumkopf sometimes …

Thanks -