PBJ-I run my EQs between the pre and power amps, vs in a tape loop. I believe, at least with my gear, the noise and distortion floor may rise with increases in output voltage, but with lower overall distortion than when in a tape loop. To STaLs point, keep the sliders in the flat position. To touch up the voices, slight amounts of boost (1 or 2 db) around 700 to 1,00hz should do the trick.