I know how it is. When I was a drummer (but one that knew about the freq. spectrum) I was in a band that split up because of this issue. The bassist was futzing around onstage with his sound that wasn't working in the room. I simply went over to his amp eq, fixed the problem in 3 seconds and we did the show with no further problems. Later in the band room he took me to task for "touching his amp." Well, it started a chain reaction that led to that band breaking up, which was a shame for me personally because I loved playing with that group. If band members would just discuss their place in the frequency spectrum, I think world peace would be achieved!
You may have saved the gig. But you did violate one of the most fundamental rules of musician etiquette by touching somebody else's rig without getting permission first. Right or wrong, that always has its consequences.
Of course you can take consolation in knowing that if that was enough to set off a chain reaction, it wasn't just you touching things that nuked the group. The critical mass was already there. So if it wasn't that incident, it would have been something equally minor down the road.
Don't you just love band drama?

