Instead of putting the adults in with moist soil, just put them on dry substrate and put a small container of moist soil in there that they can climb into. I'd put both males and females in there. Leave the container with moist soil/peat moss/vermiculite for a week or so and then put it in a separate smaller container with no substrate. Keep the humidity up in this container and you should have pinheads within a couple of weeks. I find it easiest to use a square container (or cricket corral) with a slick surface so you can pour some into a smaller plastic cup or glass and then dish them out one at a time with a small artist's paint brush.
I don't bother with pinheads, I buy 5 week old crickets 500 or 1,000 at a time, they will live for a few weeks.....long enough to get fed out before they die of old age, and to feed the tiny lings I take the back jumping legs off from the largest crickets and toss them in for the lings.
i actually found it a lot easier just dumping a couple pinheads, and watch em get pounced, than dissecting hyperactive/still thrashing adults, whcih get all stinky and moldy after quite a short while.