Even more clarification coming.
There are two products currently available: The Prodigy and The PS USB Passthrough.
Each product has their own distinct set of adapters available. Only adapters for that product will work, they are not interchangeable to the other product.
Basically, this means that you can purchase the Passthrough 901 kit, which comes with the Passthrough 901 adapter, and also purchase the Passthough 801 adapter, and 510 adapter, and all will work with just the one Passthrough from the original 901 kit. You cannot, however, buy any of the Prodigy adapters and have them work with the Passthrough device.
I really hope that helps.
Ivisi