I don't think you want 12 db of noise suppression when you record music. Even 6 db is really pushing it. I decided to couple aMGC with the noise suppression scheme, so my mod will have minimum impact on the rest of the system. I can elaborate more on that if desired.
I personally was only able to test this while blasting my car stereo at (for me) insane volumes. This still would not compare to a live concert. I was able to get decent quality audio at RMS levels of -6 dB, but I always start out at the default level. Not sure whether that may make a difference.
One idea I'm kicking around is to show a "concert" button before the aMGC UI comes up. If pressed, the levels will be low right out of the gate. What do you guys think?