Hi there. I am testing ROON multiroom with some devices. Currently with a Lumin D2 and Bluesound Pulse.
The devices where not playing in sync. Looking at the device advanced settings I found “Zone Grouping Delay (ms)” setting and added a 10ms delay to the Pulse. Much better sync now.
So far good. But if I change the settings of the Lumin (it has quite a lot, eg allowing to upsample some formats) I am finding that changing these settings requires me to change the delay. Now I can setup the Lumin to handle different rates with different settings and then - guess what - no single delay will work.
Now seriously, Roon claims it did not settle for existing multiroom protocols since these all had limitations, and instead decided to create RAAT which is supposed to do better. With Airplay 2 I have never experienced devices to be out of sync. This seems like a pretty bad protocol implementation to me.
Every device should be able to tell ROON about its internal (current and format dependent) processing delay via RAAT. The ROON software should then take each devices current processing delay into account to make sure all devices are always in sync. A great implementation is always user friendly and hidden to the user.