I replaced an active preamp with passive switch on my favorite 5-string jazz and this thing sounds so good. More articulate and open sounding vs. how it sounded with the pre bypassed. My bass, a BassMods K534 is known in gospel and funk for a hi-fi jazz sound and super easy playability. However, I'm a rootsy reggae/jazz/soul player and wanted to capture the classic jazz tone for mostly finger styling playing with flatwounds - installing this pre-amp did it. This gives me a modern, super easy playing 5-string with a rich jazz bass tone with more clarity and range through the 2 volumes and single tone knob. I like modding basses but soldering is something I struggle with. I'm all thumbs when it comes to wiring but I was able to do it with some trial and error in under an hour. If my pickups had more identifiable wiring, it would've taken me alot less - not the fault of the harness. Those instructions were clear and the unit is super solid.