Does Dante require a IP multicast capable switch?

Yes, but all Ethernet switches support multicast. Dante doesn’t need special multicast features from switches and is designed to work efficiently with advanced multicast features like IGMP Snooping.More info

Certain Ethernet switches support IGMP (Internet Group Management Protocol), a protocol that provides the ability to ‘prune’ multicast traffic, so that it travels only to those end destinations that require that traffic. If this is the case, and IGMP is correctly configured on all the Ethernet switches, then multicast media will not flood throughout the network, but will instead be sent only over the links required to deliver it to subscribed devices.

If you are experiencing multicast flooding issues on your network, you may need to configure IGMP snooping on your switch. In most cases, IGMP Snooping is not required, and incorrect IGMP Snooping configuration on your switch can cause further issues. To learn when to disable/enable IGMP Snooping, and how to configure it, please see https://www.getdante.com/support/faq/multiple-leader-clocks/