are you sure those resistors you mention aren't grid stoppers? so by two channels do you mean bright and dark, or clean and dirty (or high and low)?
what amp do you have?
i'm still kind of confused by what you wrote, but if it's any help i can tell you that a SUNN Model T has bright and dark inputs, which both have high and low inputs as well as a 'blend' input that combines both high inputs. it is the most complex input scheme i've seen. i think that's what your after so you might want to check out that schematic.