I am looking to give me Warwick Thumb Bolt on a make over. But I am not very familiar with the types of preamps there are that will fit into my Thumb 4 strings. I was thinking about going with a Sadowsky Pre, Mike Pope, Aguilar. With some Delano pickups or possibly something different. I'm just not getting the tone out of my bass that I want. I have had it for over 10 years and just can't seem to hit the sweet spot. Help.