Glenn,
I have 744T, 702T, 788T, Tascam HD-P2, Tascam HS-P82, Zoom H4N, Nagra LB and Nagra VI.
In none of these machine exists larger difference than 1dB among the inputs!
Ok Fusion with difference of 3dB, but 10dB....
If you can send me the schematic, I make the necessary corrections here in Brazil, without problem. I know as correcting these differences. If you can send for me pots and fotocelulas selected, my extra expense it will be smaller.
Thank you,
Gabriel