Big room = more speakers. I prefer better spread sound levels to higher sound levels at the front which make it too loud at front and still to low in the back. Also putting up 4 speakers on the corners of the “floor” kinda contains the sound inside the floor, creating a bigger distinction between the dance area and the rest.
2 or 4 speakers, having (a) sub(s) will add some sonic information that just isn’t there with just top ends. Sometimes it seems that people want subs just to louden up the system. As with everything, balance is of the essence. So, your subs should be set so they complement the tops, not overpower them. But when set correctly, subs do offer an extra dimension to the musical experience. Again, not just because of more sound level or freeing up the tops to do what they do best (which is not the very low bits of music, but rather the low-mids and mids), but because it adds that important bit down to 35-45Hz (depending on the sub). The part where you feel rather than hear the frequencies.
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