I can't turn it up!!

CD's with MP3's can't be turned up

, I turn the knob tell I'm blue in the face

but nothing. A normal CD will knock you out of the seat

but mp3's are just to soft. I'm recording them with nero right off my music CD's. Anyone else have this problem and maybe a fix. I have the Bose Nav system, in a 2005. This car needed the updated software to play MP3 and I think that may be the problem

??