I think you have the right idea to go with active pre-amp.
@Ralph
Thanks Ralph, like with Waz, I think you guys have the right idea. Unfortunately it didn't even occur to me. Hindsight is a wonderful thing isin't it? Its just a shame you don't have it before you do something stupid. lol.
I have 2 basses already, one being an Ibanez SDGR "something or other". It is an awesome bass with active pickups but I guess I was after something a bit different with the MMB-4. There is no way that a fretless with flat wound Chromes is going to have the punch of that Ibanez but hopefully it will find a permanent place in my arsenal.