Hiya,
My main bass for about 2-3 years was a '79 4001.
This was during my funk/metal, Mr.Bungle-type days...
That poor bass, at the worst, had (all at once):
-Series/parallel switch (both pickups in s/p)
-Badass II bridge
-Warwick-style angled tuners
and...
27-volt active EMG preamp with sweepable mids and
active/passive switch.
This was a fun one - because the Ric is so thin, there is
NO room inside for a battery (or 3

). Also, I didn't want
to take off the huge 1 pc. pickguard to change the batteries.
The solution - I never used the "ric-o-sound" stereo jack,
so I rewired it as a "power-in" jack. Built an outboard
battery box, tied it to my strap, and used a patch cord
to connect to the bass, and it was good to go.
The bass really never wanted to sound like anything but
a Ric, which was not what I was going for at the time.
However, the EQ did give me some nice options, and I
was glad to have them...you really can get a good slap
sound from those things if you work a bit at it.
(Note - the BadAss bridge was a BIG upgrade...I don't
know if the current bridges are any better than the old
ones, but I'd recommend the upgrade as a first option
if you think the bass needs it).
Looking back - it would have been easier and more flexible
to get an outboard EQ/preamp like the Fodera, Aguilar,
Tech 21 Bass driver, etc. Pretty much the same effect,
but less hassle.
Peace!
Martin