Hey, it's been some time.
Did you replace the preamp after all?
I love the stock preamp on mine.
As a matter of fact, it's the bass that's been on my stable the longest - got it from a yamaha endorser in 2008, after seeing nick fyffe playing live with those for Jamiroquai.
It's got 11 year old chromes, the same set since Jan 2012.
Its a deep mean thumpy funk machine.
With this very old set, the mid-shift-thing knob it's really useful to notch the right freq for the mix.