Update: got the Aguilar OBP-1 installed. Custom hybrid treble knob as well (pretty sweet feature).
Thoughts: The pre definitely adds some useful tones to the already sweet sounding J. Overall, I happen to like the Sadowsky pre better, but it's not OEM on the Super J's, so i'm stuck with the OBP-1. The Sadowsky pre has a more useful knob turnage, as, at least on this bass, just *barely* boosting the treble is like hardcore breaking glass territory. Still able to add just a little, but i kinda wish there were more useful knob turnage like on the Sadowsky. I was surprised that the bass knob did not behave in the same way. Overall, the bass knob could be taken up to maybe 25% or 33% from max and still be useful depending on the genre/situation. I'm sure the treble's unique touchiness has to do with the hybrid treble knob. Other than those difference, the pre does a good job of the "Jazz on steroids" thing. More organic sounding that the Sadowsky pre IMO. By that I mean the bass boost is more pillowy than the meaty/punchy 'just-right'ness' of the Sadowsky pre, and the highs are more piercing (especially when dimed). But I'm happy to have the EQ options on board. Passive it really does sound quite Jazz-ish for a humbucking-equipped bass
I dig!
What would be interesting would be to drop the Glockenklang 2-band in there (currently the standard preamp available with all Dingwalls) to see what the differences are. probably would take the bass to a more "OBP-3" level (not in the availability of the mids, no. I'm talking more glassy than the OBP-1).