Lync/S4B does not detect audio device in client when
there is no Mic inbuilt in audio system.
Check
if connected sound system has mic inbuilt...
This scenario will take place, if you use workstation class machine and most of such machine does have sound system with speaker but no microphone inbuilt in it.
In this case, Lync will not detect any audio device in client, hence in order to use audio in client, you need to connect sound system with speaker and microphone.
