Command Line switch & Curl : How to pretty print response?

Try use jq instead of python -mjson. It would be something like:
curl -X GET ‘http://192.168.xxx.xxx:8080/BeoZone/Zone/ActiveSources’ -H ‘content-type: application/json’ | jq ‘.inUse’

Or have a look on this post to try fix the use of python on the command line switch:

Hope it hepls