JazzGroove public URL’s are freely available but they also offer FLAC SQ on their subscription service. Originally the FLAC service could only be accessed via their webpage. Recently however they are offering a URL to subscribers which includes a subscriber token. The URL with token included can then be pasted into ROON as a ROON radio station with FLAC SQ. It’s in BETA at the moment and there are reports of dropouts but hopefully that will be resolved in time. So subscriber stations can be added to ROON but it needs the support of the provider I guess to implement it.