In some rare situations, you might want to unlock it so that you can EQ the left channel differently than the right.

It is possible to compensate for inequalities in the layout of the car by adjusting the left and right sides differently. The car is not symetrical, duh, and everyones' listening position is less than optimal unless you own an F1.
to account for the meter bridge (dials'n'guages bump in front of the driver), some installers boost or attenuate the frequencies on that side (apparently). There may be other irregularities in the car which requires you to unlock the left and right side, but these adjustments would only be minute.

Q is a fun thing to play with if you cannot see the frequency curve you are creating. It can be argued that it can be done, but is best left to the professionals! The default adaptive Q setting currently available is quite good and doesn't really need to be messed with.

As for what 'special' settings could be created for different types of music, it still is subjective and specific to the environment, components etc. As a 'rule', jazz can be cut back in the bass; classical could be boosted in the mids except for woodwind predominant pieces; Rock cut the mids as vocals and distorted guitars can get wearing after a while; club/techno, cut mids & slight boost to bass and tops (within the range of the EQ so you dont get digital distortion); Vocals boost upper mids and cut lower mids but it depends if it's male or female.

Adjusting EQ is totally subjective. For more information take an audio engineer course (then tell us the settings ) The important thing is that it sounds good to you and you don't get tired of listening to it. That is the first sign of bad EQ. Your ears get tired quickly and give you headaches or start ringing.
Ever go to a concert that wasn't overly loud but your ears hurt? Ever go to a bar and even though the music is loud, you can easily carry a conversation with the person next to you? Examples of bad and good EQ.

So. Play with the EQ and save settings you like. then try them out over the next week or two. see what works for different styles. This is more important than me saying what should sound good in your car, I don't have to listen to it.

That's enough from me i think. Is that some kind of record for longest thread with fewest number of posts? {whew}

Murray 06000047
I don't think, therefore I am not.