What I mean is that with 100 listeners spread out over an auditorium, they will all individually experience a (slightly) different effect from sound propagation delay. There is a point at which you can't improve the experience for one individual without degrading it for another, so no ideal/perfect solution.
Active EQ processors typically deal with standing waves interference, particularly problematic on low frequencies proportional to the space and (the unit you linked to) feedback from that in relation to static microphones (you tune the EQ for the mic position). I have an active EQ in my ... err ... "man cave", to tame LF in the listening position. Wander around the room and you soon realise the problem didn't go away, the processor just moved it to somewhere you didn't care much about. Easy with few people, increasingly difficult as the zone you want to compensate for widens.