About that "Jazz Growl": Last night, for some reason, I deviated from my normal feather-touch playing and plucked the crap out of the strings playing fingerstyle r&b grooves all night on my relatively-new Lakland Darryl Jones 5 (bridge pickup, playing close to bridge, some low-mid boost on the head). I have never heard this bass growl so much before, and I loved every second of it! Lightening up my touch a bit, the growl went from aggressive and in-your-face, to polite and boring. I don't know if I really like playing so heavy--I'm much faster with a light touch, and the heavy digging left my wrist pretty sore. Any ideas on how I can achieve Maximum Growl™ without having to play the crap out of the strings? Will compressing the signal help or diminish this sound? (I have a rarely-used Demeter Compulator.)
I would say start experimenting with different amplifiers and cabinets. I had no idea of the importance of the right combination of your gear but it does make a HUGE difference. Another thing that I found out (probably most people know) is that passive pick ups allow you to sound with more distortion than good active pickups. You can also try to use smaller speakers like 8" or 5" or a combination of 15" with some other of smaller diameter. I also used in the past a Peavey ProBass 1000 preamp to try to control the frequency range. I think this was kind of useful but it added some noise.
Sounds like you might have been getting your tone by slightly over driving your amp. Maybe just increase the input gain?