I run subs with large speakers. Without the subs my system is just ok but with the subs it is outstanding. Bass really matters and does make a huge difference
All speakers need subs. Even wilson audio runs subs with their supersize speakers. Unless the speaker is active all speakers improve with subs.
With big speakers you need to use a highpass. If you look up the measurements of your speakers and cross them over where the woofer starts to roll off before the port picks up (probably 60hz) it will work out pretty well as a starting point.