Cd changers are almost dead
You should have USB on a newer car load up a USB stick with your favorite tunes . You can get far more tunes on a USB stick and it will never have a mechanical failure , also you can edit it or put new stuff on it . Use and ipod if you don't like that or your phone may be capable of some music storage .
Also I think the hard drive in the Nav Unit is capable of storing some tunes.
It does have a single CD and if you load that up with High Quality mp3 you can get 50 or 60 tunes on one of those disks more if low quality.
There is a sticky at the top of the page for eq setting for L7 stereo