I used to do this using my Line6 X3,
I can't remember the settings but being able to run two signal paths through it meant I could have a clean, punchy bass, and a massively overdriven, crunchy tone together.
You can run both tones through different preamps, eqs, amp and speaker sims to get the sound as crisp or muddy as you want.
I used to love doing it because the bass sounded huge