Hi,
While Rose has modified their newer designs to have integrated wifi and bluetooth, for the older units like the RS520 which use external dongles… you’re stuck with their dual purpose dongle (wifi / bt) which limits you to BT 4.2 only.
Rose could modify the OS to allow for different BT and wifi drivers but AFAIK, the AndroidOS version used is not the latest release and this is causing issue w Spotify.
That said… there is an alternative that could help.
You can get an external BT transceiver.
I have the McIntosh MB20 which retails for around $500.00 and they have a more expensive MB25.
Both are BT 5.0 but you can get an iFi device for around $250 that is BT 5.4 so if your transmitting device is also BT 5.4 you now have lossless BT.
That said… I tried using my MB20 and the optical in on the RS520.
Running BT sound from my Macbook to the MB20 and using the toslink in… much better sound that using the dongle.
I would hope that Rose can update their OS and to also find alternative dongles (wifi and bt separate)
Currently I’m running a CAT8 wire to my switch and then w the MB20 bypassing the dongle all together.
(except for the remote).
Just some food for thought.