A standard ritual I have had after each preview build is rebooting to get sound working (clear audio icon of the X in the System tray). Today after 14295 that did not work. This is a bit surprising because I have just read John Wink's description of all the great troubleshooting that Insiders have done for them in this area. But it is also surprising because this is a standard Surface 2 Pro (running 10586.164) that this is happening on.
One recent change which may have something to do with it is that previously I had my Surface 2 Pro docked and my external speakers plugged in. Now, to try to get more real tablet experience with W10 I have given that position to my Surface RT and use either MouseWithoutBorders (mostly) or the Surface screen cover for typing. So, speakers for both the VM and its host are now only the Surface 2 Pro internal ones. However, I have checked and do get sound from them for the host.
Another change which I suppose is slightly related is that in order to use my wide-screen monitor I have had to start using a Microsoft Wireless Display Adapter. Since that is HDMI I guess there could be some audio component involved with it. Another option would be to use the Surface Pro's Display port and wire it to the VGA port with an HDMI-VGA converter. The RT is using the other HDMI port on the monitor.