It's gratis and open source, but they offer some 'premium' features as a service. I used volumio at home in the last few years and it was good overall. Only an

It's gratis and open source, but they offer some 'premium' features as a service. I used volumio at home in the last few years and it was good overall. Only annoying thing was trying to get multiroom audio working ... I eventually did, but it took a lot of hacking around. Maybe it's easier now, I don't know.