Is there any alternative to the Marshall Bluetooth App for the Acton / Stanmore II / Woburn Series?

Specifically is there another way to link up two speakers to a stereo pair? Maybe a desktop client or maybe even a command line tool?
Or is anyone aware of an e.g. an open source project that reverse engineered the protocol? I can't be the only one out there finding the app horribly unintuitive and poorly programmed, also some functions simply do not work - e.g. source selection for a coupled pair.

Thx...

When I connect my Code 50 to my PC via USB, it only plays the left audio of music but not the right audio. This problem does not persist when connected via Bluetooth to my phone.