Yes, of course I meant to cast no aspersions on your actors, but only to make the case that in situations where natural projection doesn’t cut it (as in your scenario), you need the proper equipment, or else don’t waste your time/money.
Unrelated to your situation, I have run in to situations where amateur, untrained (and even unrehearsed) individuals were called on to support speaking parts in a stage play and they had no concept of “stage presence”. They mumbled to the point that even if you were standing next to them, they would be difficult to understand. They expected the microphones to perform miracles. Never gonna happen.