I've had a pretty easy time cleaning up the first channel without the mod, actually. I have the gain slightly below 9:00, treble turned up, mids turned down, and I'm pretty happy with the clean tone!
I'd imagine the mod they're doing is to adjust the taper on the gain knob. Maybe there's no noticeable difference in tone, then? If someone can A/B them, that would be cool. Otherwise, I'm perfectly happy with the clean tones on mine, which again, is not modded.