Spaced omnis - two to three feet apart - are good, but not as precise in localising sound sources as cards. But the do give the ambiance and "warmth." The distance ratio of omnis vs cards is1 to 1.7. A card hears at 1.7 what an omni hears at 1. I understand cards can also be run as a spaced pair, like omnis, if you are pointed at the stacks. If you can, try as many patterns as you can on the opening act. Otherwise do what we all do, wing it! Good luck.
