SX volume/sustain issue... bridge?

hello peoples, the time has come again for help from TB.

i have a new SX jazz that i like a lot, except one thing. i can not seem to get it to sound right.

i am experiencing:
good sustain and low end on the E string.
terrible sustain and low end on the other strings.
low volume, not cutting on G D A strings, especially around the 7th fret and higher.

i play through a mid heavy cab with a flat amp EQ.

what ive done:
replaced strings multiple times.
replaced neck pickup with old dimarzio model J.
hard wired the model J with SX bridge single coil in series straight to the jack.

i have noticed that on every other bass i own, i bottom out the bridge saddles just fine and set truss rod for good action. i have never had a problem doing this.

this bass will not let me bottom out the saddles, not even close, otherwise the strings are pressed on the frets big time. i have a SX neck on an old p-bass and do not have this issue.

help?

 

any takers? should i go ahead and get a set of model J's like ive been thinking? switch necks/bridges?

 

for anyone that may or may not care, it seems i overlooked a few things. after thinking, i grabbed my P bass to compare setups. my P plays exactly where i like it to be. action is probably high for most to help me get a meatier tone, but does have some fret buzz. no dampening notes or anything coming through an amp. it mainly happens from aggressiveness.

note, i did not take any measurements for when it plays nice it plays nice. obviously had i taken measurements long ago, this would not be an issue. duh.

anyway, i checked relief in both instruments.
P: fretting 1st and 20th frets, the gap between the string and the 8th fret was about the same height as a fret itself.
J: doing the same, the string was sitting on the frets. i immediately loosened the truss rod approx. 1/4 to 3/8 turn to achieve the same relief.

i then noticed the action was still lower on the problematic J than the glorious P and had some undesirable buzz. i then raised the saddles a tiddly bit.

the J now plays much more similar to the P. not identical, but a lot better. thicker resonance, longer sustain, not so dead sounding, more equal response throughout strings/frets. ive been setting up my basses for awhile now, especially after stumbling across talkbass, and youd think with a new bass id pay more attention to the set up. i guess i had the ol set it and forget it attitude when i first received the bass. good lesson to learn.

the real test will come at next practice in a band setting.