My P with flats sounds like a P with flats. Caveat, it’s a P/J with a toggle to solo either pup. Bridge J pup with tone backed off on the bass gets the Jaco sound.
I have a Streamliner and B-arrays bring out that sound, specially with the 12-3. My Music Man Stingray sounds awesome through these cabs. They are pretty transparent and bring out the unique sound of whatever amp and bass you plug in.
The only sound I don’t get out of my 10-2 or 12-3 is the “SWR sizzle”, which every once in a while I miss when I want to play around and slap but haven’t needed for gigs in many years with the stuff I’m playing now.
Is slapping still a thing?