It's more flexable than you might otherwise think, but you do have to be very deliberate in your choice of freq to either cut or boost and by how much.I just ordered a Rumble 350 head this afternoon and I was going by those pics. To be honest I didn't even notice it was different than the 150 head I played on.
If you're playing live, you really need to go out about 25-30 feet and carefully experiment and choose your mid-freq to boost/cut. Don't just go by some textbook. If you've got some friendly musicians (other than bandmates) during sound check get some feedback on your tone.
I've found the bass is most natural at noon with 0 boost/cut. I then always cut the 10K treble by about 5 or 6 dB or so. The most critical for sitting comfortably in the mix is the midrange. I tend to cut the high mids right around 1kHz, but not too much. -4 or 5 dB or so. Gets rid of finger on string noise, attenuates some fret buzz (if your strings are too low or you're a sloppy player = clean up your act!) also subdues 'pick-click' if you're a flat picker. Also helps to attenuate dreaded string screech when playing rounds. On the V3 D-Class the Hi-Mid control at 1.2kHz is good to cut accordingly.
Wow, BloozBass, just WOW! 

