“A solid studio mix, properly executed and EQ'd will sound good with most systems without a need to create a custom mix. If you take the time to get the mix right with some quality flat response monitors, it will sound good on everything you play it on.”Actually, it won't. Mono vs. stereo mix, frequency response variables between stereo or monitor speakers and PA enclosures (especially bass response), dispersion, cabinet design – many reasons. SOS addressed the topic in this article:
http://www.soundonsound.com/sos/nov03/articles/backingtracks.htm “It can be very hard to judge the playback mix while you're at home in your studio, especially if your studio uses small speakers. Large PA systems give a very different bass response, and rehearsal-room monitor speakers will introduce their own 'idiosyncratic' tonal characteristics! When it comes to committing to a mix, a practical solution could be to take your original multitrack machine (be it ADAT, Tascam eight-track, computer or whatever) to the rehearsal room along with a small mixing desk. Then you can set up each song and have the band play along to it, while a band member stands in front of the PA speakers and makes a judgement about the mix of the mono playback material.”
Duplicating this situation for the OP would require setting up his PA and mixing his backing tracks in mono through it.
The “room” has less to do with the final sound than the mix that is matched to that particular PA system.
Regards,
Bob