[e2e] Protocols for tightly synchronised multicast?

[Simon Spero]

Does anyone have any suggestions for a multicast transport capable of
delivering packets to applications on multiple clients synchronised to
within a few milliseconds?

The idea is to try and build a distributed virtual sound-system; a single
source would send a single stream of audio data; this data would be
recieved by multiple clients, with the data sent to each clients speakers
with a fixed delay relative to some global clock (the delay would be based
on the client's physical distance from the center of the virtual system,

I can see how one could roll ones own using timestamps and NTP, but it'd
be nice if I could use an existing transport

Thanks for any suggestions

Simon