He said he's mostly music, so I assumed SACD which is designed for 5 identical speakers.
I think I screwed up saying there isn't much "info" below 40hz, that's not accurate. What is should have said is, most of the bass we actually "hear" and can cleanly define resides in the 60-250hz range.
To elaborate, while there aren't many instruments that go below 40hz, even more relevant is that our ability to hear at those frequencies is compromised, we're more likely to feel them.
For the average human, to "hear" a 20hz signal at the same level as say a 100hz one it has to be nearly 50db louder. Not only that, because the waves are so big our ability to hear distortion decreases as the frequencies get lower.
A subwoofer is condsidered within spec if it's under 10% THD, I don't think anyone would accept that with a speaker.
Current Gear: Anthem AVM60, D-Sonic 3500/7, Oppo UDP-203, PS Audio Nuwave Phono Pre, Technics SL1210 w/ Denon DL103, Dune Duo 4K, LG Oled55e6, Paradigm Sig. S6 & C3 v.3's, Monitor ADP's, Velodyne SPLR1200.