I also think one needs to match their ampage to the instrument. Does one really need a rig that will go 8hz to 20k hz ? From discussions in previous threads, the instrument range just isn't there. If you play 4 string, your low fundamental is what 41.3 or there abouts ? And from the previous discussions getting out to 6k to 7k is a stretch. Of course 5 or 6 string basses are another story.
I'd agree with Keith that 10's and 15's cover most of the range needed. But with todays technologys, 10's and 12's are getting down in range to match alot of 15's.
I do sometimes miss earlier times when when you plugged in to 1 of 2 inputs and there was a volume, bass, & treble knob. And no horns in the cabinets.
I'd like to hear Tornadic Thunder sometime, bet that could make your hair go straight back (think wind blown effect)