Parece que o icecast não tem restrições de stream e, portanto, as únicas coisas que limitam a quantidade possível de fluxos simultâneos são o SO, o hardware que você usa e a configuração do icecast conforme declarado aqui .
Trecho de aqui e aqui :
Pergunta:
Is there a theoretical maximum to the number of mountpoints icecast can handle?
Resposta:
As for limits: yes, but it'll be highly platform specific, and is not a limit in icecast itself. You'll probably first hit either a limit on the number of threads permitted (one per source, plus a few for the rest of icecast), or the limit on open file descriptors (one per source, plus one per client, plus a few for the rest of icecast)