you don't need a unity gain at all. it just isn't imprtant like people make it out to be. just choose one spot on the preamp (like, say 9 o'clock on the dial) and set your pre/pro levels for center and surround relative to that. then, whenever you watch tv or whatever, just set your preamp to that input and volume spot. then the pre/pro will handle volume for all non-music sources.
