This is very interesting. It seems to me, based on experiments, sound quality can be improved by minimising workload of switches or routers. Your suggestion helps with this.
Can you clarify what settings need to be off? My router (Mikrotik CRS 305 running RouterOS) has IGMP Snooping off in it’s Bridge interface settings (this is the default). From a bit of reading it seems this setting disables various other multicast features, which highlights each router software may have its own interrelationships between settings.
I also note most audiophile switches are probably not managed.
As an aside Synergistic Research has recently released a router which appears to use a Mikrotik router board.