I just started playing the game about 45 minutes ago.
The Hofner is either junk, or auto-calibration doesn't work.
It seems to drop most of the hammer on notes. It's quiet, but it requires much more force to push buttons down than it should - possibly why the hammer on notes aren't working.
If I can't get it to work well, I may trade it in for something a bit more sturdy and responsive.
I can't even enjoy the game, since it won't stop breaking combo.