I'm no expert on mics or sound-setting, but I've had experience with them. Mics are amazing; they allow you to be more 'in your head' with a song. You can sing and feel your message without worrying about getting your voice to the back row.
I do not think Adam's microphone was 'turned down' in his performance with Angie on Idol.
Had it been, we would have experienced an overall muting of sound; including the softer notes. Adam's tone was so pure, so present - I could have harvested it from the tree. His fruitful voice was that ripe. Nothing was muted or toned down as he sang '. . . up'.
What we saw - and I keep watching, over and over - is, as someone said - a 'maestro'. He modulated his voice by moving the mic closer, and then further away. Of course, it wasn't just the mic. Adam knows his tender voice; and he brought it out in force.
I've sometimes wondered why Adam doesn't wear one of those microphones that are attached to the head; like Britney and Bieber and most others. Of course! It's because he's singing live and he knows how to accelerate and pull back; and the distance of the mic from his mouth - that
he controls - involves the emotion and message of the song; amplifies his need to convey all of that without blowing out the amps. He did this in 'Titanium'.
Adam knows how to pull back. He knows how to make his sound more mellow - and he doesn't need a sound tech to do it for him. Someone said, on the thread, how they love his duet on 'The Prayer'. Nothing more needs to be said. This man knows how to shine; and how to give others the sheen and the sparkle and the moment.
LWOG is another story. Here, I think, the microphone WAS turned down. We heard the track, and Adam's live singing was there - but quieter, overall, than the acoustics of the 'performance'.