given my previous post was almost a year ago... I had upgraded all MK1s in my bass already.You should go with the audere classic 3 band , I just put one in my 55 01 and sounds natural , no coloring at all
I went with Bart HR-5.2AP/918 pre-amp (not the HR-5.4AP/918) to accompany the MK6 pickups, cause turned out it was ready at the time. It also turned out to be better fit with my plan of installing a mini switch for pickup coils split without requiring to drill a new hole, since this pre-amp uses pull-push mid pot for mid freq selection instead of a dedicated mini switch (as if I insisted to wait for HR-5.4AP/918), whereas my bass only has 1 hole to accommodate the MK1 pre-amp on/off switch.