Splitting individual strings on jazz bass Bartolini 9V Quad pickus

I have these rare Bartolini Jazz Bass 9V Quad pickups on my Doug Roomian bass I asked to be built custom splitting the two lower strings from the two higher strings using two jack outputs.
Now I would like to emulate my current mentor Michael Manring Zon Hyperbass with a custom Bartolini pickup that allows to split each strings with a multipin din jack going to a splitter box using a XLR plug and four 1/4 jack outputs.
I found a splitter box from Galaxy Audio with four 1/4 jacks outputs and one 1/4 jack input.
I also just purchase online a couple days ago a used Godin 5 string fretless with the RMC multidin output for Midi were I would like to do the same splitting the strings individually.
I'm considering using Bartolini's two 2 channel buffers in the Roomian since the Hyperbass uses buffers. Any suggestions as two how we could wire both pickups in parallel to have four volume knobs on the bass and ignore tone control and install a multipin din to connect with the splitter box. I'm looking for using two amps with two preamps each for the Roomian and add a third amp for the Godin 5th string. I feel very fortunate to have these rare Bartolinis only manufactured for a short period. I feel like finding a classic Ferrari forgotten by time in a farm barn. Cheers