When you raise a pickup..
it can get close enough to the strings to pull them out of tune when they are vibrating..
it can overdrive the preamp and actually distort at clean settings..
the neck being in a position where there is much more string vibration, will overpower the bridge where there is little if they are the same distance from the strings.
either pickup lowered away from the strings will become less loud, lose tone, usually lows.
Since the neck pup is set so close to the strings to begin with.. many lower it until it is flat or nearly flat in the mounting ring.
This allows them to raise the bridge pickup to it's optimal tone and volume position, then blend the neck pickup to that.
adjust your bridge pickup to a pretty low setting..
raise it a bit..
listen
raise it a bit..
listen.
do this on a clean setting and you'll see the range it has and you'll also develop a personal preference.
When finsihed, do the same with the neck pickup.
when you think it's good..
then use the middle switch position and compare the mixed tone..
you should be going for optimal tone and volume, to your taste, compromising for the middle position to gain a balance that you can live with.
TWANG