I have an amp that is super loud but I was not able to dial in my sound using the amp's onboard preamp. So I did some research and on a whim purchased the Startlifter Bass Pre/DI. I run it into the effects return of the amp now.
What I like: Tones galore with minimal knob twiddling. The preamp adds just a little bit of musical distortion when you want it. Layout is super simple. Connectivity works for me. I have my sounds now.
What I don't like: It is surprisingly heavy for its size and a bit large. It requires a specialized AC adapter with 12-15 volts.
Even with the couple of dislikes I can live with it. I would gladly carry this somewhat over sized and heavy pedal with a weird AC adapter to achieve the sound I'm getting out of it. Its a trade off but tone is king in my book.