Agreed with jb63 and DP.
Omnis will sound more natural and magical when you get it right, and can work well in this kind of situation, with teleportation time-machine like potential.
2 feet apart will be good up close and might be easier to do, which is about arm-rest-width in row seating, and probably easier at a table too. Spaced less than about 1-1/2 feet is when a baffle of some sort will do most to improve things. Anything works in a pinch, like a handbag, a coat, menu, table cards..
One thing to be careful of is if the PA is much louder than the performer, in which case you either need to be really close to the performer, or make sure you pickup enough clear PA in addition to the direct sound from the performer. That direct sound from the performer and instruments contains the magic juju! If it sounds good right up front in the center (with no muddy off-axis PA zone there) get right in front with the audience behind you and everything falls perfectly into place.