I have a Yamaha BB605 and got so fed up of the stock pre that I swapped it for an East U-Retro 5 knob Deluxe and it's a fantastic preamp but I chose it because of it's full passive mode with tone control. The preamp uses a passive blend and tone control with a hybrid volume knob which means you get true passive vol blend and tone in passive mode and you get passive tone and blend with active volume and variable 3 band eq in active mode so you get a very nice and very usable set of basic tones before employing the tone control and eqs. I'd seriously recommend checking them out, also John East is a very friendly guy (and a member on here) and his site is very informative.
I use my BB605 with stock pups in passive mode about 60% of the time and use the active mode for a distinctly different tone, be that huge Dub bass or grindy mid boost or HiFi slap tone etc then I just have to knock the tone push/pull down and I'm ready for a solo or song shift or just some fun!
(along with the bartolini 3rd pickup I added this preamp has hugely expanded the usefullness of this bass)