A drop ceiling has a lot of advantages over drywall, and the only downside is more sound leaking to the floor above. But if sound isolation isn't an issue, a drop ceiling is great.
The best tiles are made of rigid fiberglass. Years ago Armstrong sold high density rigid fiberglass tiles up to three inches thick, though I haven't seen those in a long time. But you don't really need that. Instead you can use thinner rigid fiberglass, with thick fluffy insulation on top where it's out of sight. The only problem then is that thick insulation above the tiles makes it more difficult and less pleasant to get to the wires, which is your whole point. So instead of covering the entire ceiling with insulation, you can leave a path for the wires. But you do want thick fiberglass around the perimeter because that's a corner that benefits from bass trapping.
Home Depot sells 5/8-inch thick fiberglass tiles with a plastic surface. So here's what I'd do: I'd install those tiles as intended everywhere except the loudspeaker reflection points. For that cluster of 4-8 tiles I'd flip them over so the plastic is above the grid and the bare fiberglass is on the bottom exposed to the room. You can use spray glue or some other method to attach cloth to hide the exposed yellow fiberglass. Then put fluffy insulation as thick as possible above all the tiles, especially around the perimeter, but optionally leaving a few places free for your wires.