Here's a quick unrehearsed riff using my BOSS SE-70.
Notes: I've been playing bass for about a year and you'll hear that in my playing and picking technique; I have a silly high gear-to-talent ratio; I have limited recording skills even though I've leveraged those limited skills into a mostly passable demo for my current band.
Signal chain
* Lakland Skyline Duck Dunn with Lindy Fralin and LaBella Flats, tone rolled probably half way off
* BOSS SE-70
* Line6 M9 (DSP bypass, been testing it and forgot to unplug it from the signal chain)
* Aguilar DB791, treble cut totally, mids 1 O'clock, bass 12 O'clock, no bright or deep
* DI out into M-Audio ProFire 2626
Clip includes the following:
* Clean sound
* Fuzz sound 1 using Guitar Multi 1, comp, fuzz, eq, noise gate
* Fuzz sound 2 using Guitar Multi 1, comp, fuzz, eq, noise gate
* Fuzz/distortion sound using Guitar Multi 1, comp, crunch instead of fuzz, eq, noise gate
I can't recall what tone/eq I leveraged, but I usually cut the tone settings in the comp and fuzz/crunch to shave off treble, then in EQ cut the sub bass, boost low mids, usually scoop some mids around 800-1K, and further cut the highs.
This is just a small sample of the possible dirt sounds you can get out of this thing. There's also overdrive which to my ears sounds merely OK (high noise floor which is obvious even with a tight noise gate) and sounds best out of the Bass Multi algorithm as it includes a dry blend. There's also Guitar Multi 4 algorithm which also provides a blendable dual signal path for dry/guitar effects, which you'd theoretically be able to leverage to blend your clean bass signal through. But Guitar Multi 1 which I've chosen for my fuzz/dirt as heard does NOT include any dry blend at all, that's pure effect signal.
The sounds seems much more bass laden and full to my ears when pushed through my Accugroove El Whappo Jr vs listening back to this recording through my tiny monitors.