I recently entered the world of mustang basses and fell in love with blue JMJ model. That neck is sooo good. I play is all the time at home. I do have issues when I run it though my gigging bass rigs. Either a Super Bassman with a Fender 610 neo cab or My Ampeg V4B and 212 AV depending on the size of the bar. On the other hand, my pos practice amp with a tiny 5" speaker sounds great with it haha. The A,D and G sound amazing while Running Chromes on the bass. The E string wants to disappear in the mix however. So far I've found very thin .50 picks will make that E pop out but I'm not having lots of luck with fingers or thicker picks. My hand gets tired fast using the little paper thin .50s! I'm used to P basses with TI flats so its been a bit of an adjustment for me. Looking for the sweet spots with my eq, compression ect for this bass.
Huh...well that's weird. A few things come to mind: 1) Change the strings, you could have a fault. 2) Adjust the pickup heights to compensate. 3) Aggressive parametric spot eq. I'm sure other folks might have some ideas for you too.
I hadn't though of it possible being a dead string. I've had this set on and off several basses. Worth trying a new set. Even after rising the pickup the E is still acting odd.
It could be off-base but it does happen...but yeah, I have two JMJ mustangs and my E sounds great...of course in that particular short-scale way.