In November 2015 I heard from Jeffrey Langerak:
"I've recently played with a Sun Ray 2 thin client.
The network chip is a VIA VT1603L and the audio is handled by a WM9705S.
I've installed Solaris 11 on a spare X86 machine and installed the Sun Ray server software on it. I was able to let the thin client boot from the Solaris server and log in to the desktop that the server offers.
That runs pretty neat and sound is being redirected to the thin client nice and easy. One thing of note is that you really have to disable the background as this slows down the rendering process sometimes. But then again I've installed Solaris on a 8 year old machine which may also work against the rendering!"