I've found some details of the PCB:
https://uk.rs-online.com/web/p/audio...dules/0434065/
There's a link to the datasheet on there. As you can see, it's just a case of fitting the passive parts you need.
If you'd like it, send me a PM with your address and I'll get it posted. It might take a few days - it depend on when my wife can get to the post office.