In the release build of the LL viewer this works fine. This is ONLY in the RC 7.1.9.10326512121 build (and Firestorm 7.1.9.75794 which is based on this RC code)
I set voice to input and output using my Plantronics Headset. On the live LL client this works as it should and all other sound is sent to my default device which is my iMac speakers.
With the RC client all sound is sent to the default device and it takes input from the default mic on my iMac but there is a very quiet "echo" of this being played on my headset as if it is also trying to use that.
This currently renders voice inoperative for me as I am unable to use a headset and it defaulting to use the iMac speakers for output plus the iMac mic for input results in a great deal of background noise in addition to echos caused by feedback.