As the ever evolving double bassist, I've decided to try out a new amplification system. I am currently set up with a Fender Rumble 350 head into a TC Electronic RS210 cabinet. I've got a Hurley preamp and two pickups. One clicky set under the fingerboard and the other a regular Piezo wedged into the bridge wing. The 350 head has an input impedance of 1M Ohm. I'd like to get rid of the preamp and after some reading, I see that with this kind of input impedance I could do this successfully. The question is this. What would be a good pickup to use in this situation? I feel that I can get away without the clicky pickup because Im going to install a set of Spirocores and change the gut strings out. I'm playing more jazz and I feel that the clicky is more for very heavy Rockabilly or Psycobilly. My slaps do NOT need to be so far out in front of a very loud band. I'll still be slapping plenty but for my purpose, I believe that one pickup will most likely work for me. Is there a particular spec on a piezo pickup that I want to look at?