can't you use it as a bluetooth speaker for your phone and just use the app?
i guess not because it uses WIFI and just wants the audio file.
too bad you can't just use it as a remote speaker for the mobile phone just reencoding
honestly there is no reason not to support low sample rates.
the speaker system has to resample them anyway.
also "protecting" the user from "bad" content is just stupid. they could have a warning: low quality not the speakers fault lol.
anyway there are a few streams with 22kHz.
listen to JFK tower for example
Have you actually contacted the customer support and told them about your problem or how do you know "why" they are not supporting more formats?
edit: also there seems to be a line in option on some of those speakers? so you can connect an old mobile phone with a cable to listen to liveatc?