Glad it's working.

If you can face it, it maybe worth checking how to enable IGMP snooping on the managed switch to avoid future problems. I think I read it's disabled by default hence yur issue.

You need to configure it so that multicast works without a multicast router on the network, i.e. the switch works out what ports are involved in a multicast group by itself instead of waiting to be told by a multicast enabled router that is not present on the network.

Or tell all ports to open for multicast, i.e. treat multicast as broadcast, as is how most unmanaged switches operate which is why it works out of the box for the unmanaged switch.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).