It's true that amateurs (and some pros) will frequently blame a poor performance on the technology or the sound tech. It's also occasionally true -- a singer who can't hear well onstage needs to either have the experience, the training or the inate talent to sing perfectly on key. The amateurs rarely know how to define what's wrong, and resort to saying the monitors aren't loudn enouhg, which may not be the problem at all.

But that doesn't seem to be the issue here, I think. Amplification is a totally different feeling, whether it be singing or even playing an instrument plugged in for the first few times. It takes some getting used to -- and why do I never see voice classes for microphone or studio technique?

Of course, sometimes techs have been known to use the placebo effect and swap out perfectly functioning equipment (or pretend to) to give a performer having an off night a mental boost :) Even an old pro who KNOWS his less than stellar performance is his own fault will fall for this trick!