But, the PA system is usually stereo. I’m not in the techno-rave community, maybe there are innovative techniques being employed there but I never heard of M/S encoding a live stream to avoid “rumble”.
Nor do I anayse what you mean by “rumble” exactly, I must admit. I can identify phase issues when I hear them (that’s part of my daytime job), I have handled many a “rumble” issue when using turntables live on high-power PA’s, (or rattling furniture and breathing walls and ceilings) but “rumble” coming straight out of the OT (or otherwise pure electronic devices) is a discovery. Unless you simply have more LF content than the house PA can handle, or content including high power frequencies below the system’s specs which leads to a frequency-modulation effect in the low-mid and bass parts which basically is a LFO on the bass frequencies. The speaker cone is then moving slowly (like 10 HZ) at maximum excursion, and the “normal” bass frequencies (50HZ to 120Hz) are modulated by this oscillation because they are carried physically by the same speaker. The more elastic the cone suspension the more dramatic the result.
Maybe just cut off LF under 30 HZ would solve a big part of the issue. The DJ-style EQ on the master track is a quick problem solver in this context.
And you should forget about competing live with professionnally mixed and mastered content. The OT is one hell of a box, but it can’t do everything on it’s own.