I watched the past two seasons of NBC (US)'s show "The Sing-Off" which pits acapella groups against each other. The groups range in size from five to fifteen or so members each.
For opening numbers there may be sixty or more singers on stage, each individually miked, and it doesn't appear to be lip-synced or post-scored.
What equipment (radios etc) and techniques make this feasible? It seems like an impossible task. War stories appreciated too, if you were there.