I have a warwick Fortress One bass, and I am happy with the sound I'm getting out of it. It's just that It's not quite deep enough for me. I've done some reading up, and it seems that Bartolini pickups would be a good choice for a replacement, but I'm afraid that I would take away the "warwick" sound. I like the growl of my bass, I would just like it to be a little warmer. Would replacing the preamp do the trick? Are there any pickups out there that produce the growl of MECs, but with more low end? I appreciate any opinions and comments.