Well I’ve now got it installed, and fixed one problem, created another.
Fixed : Firefly now serves to Rhythmbox (linux media player) fine – all mp3s now play.
Broken : The old pcast (mt-daap) based player worked fine with my Vistron radio when I went to UPnP servers, the new firefly doesn’t show up at all.
The pcast was using 8080 and 8000, whereas firefly is using 3689. Could this be the problem?