Would you be happy with Bluetooth speakers?
I do not normally recommend these but they are cheap and easy to use.
I have several and all work OK over a limited range. You will need to connect a Bluetooth
transmitter to your organ's computer if it does not already have one. Beware of latency.
Try to check this before you buy.
All of the systems I use Bluetooth with have built in Bluetooth transmitters so I cannot
recommend a specific transmitter..
csw900