The only practical way to approach sub-100hz notes in a bass rig of a reasonably manageable size is ELF (or INFRA). Without it, you can have your own WallofSound, several big amps, a van, and a couple of stout brother-in-laws to help.
I went through this and came out the other end feeling this way: Most of the bass we hear well is around 80 or 100 hz, which most cabinets can do pretty well. Remember, the low B fundamental is TWO octaves below this, and they happen to be the two hardest octaves to do right. Ever see the massive 4-18 subs that Touring Sound companies use? They ain't just for looks, you're moving BIG air in the 20-40hz range.
Out past 4 or 5k, there's nothing going on for a bass guitar in a practical sense for my ears.
Try this: Next time you're around a electronic repair shop, most scopes have tone generators in them that will make pure tones (no harmonics), and listen to Low B. Hear these tones, and a lot of this becomes academic real fast. It dawned on me I DON'T need a PA or Studio Monitor response for bass.
There's a big difference between pure laboratory specs/response and something that sounds musical.
I'll take musical every time.
J o e y