When connecting to Windows Server 2008 through remote desktop choosing to leave the audio on the remote machine does not work as expected. Although the option shows up on the remote desktop application, if you select it and then connect, the audio is simply disabled as if you had selected the “do not play” option in the application.
This behavior is by design. Server can have more than one active session, so it can lead to problems (including privacy) when trying to use the "leave at remote computer" option. Because of this, the server will automatically roll over to the “do not play” option when the "leave at remote computer" option is selected. There are no workarounds for this behavior. The "leave at remote computer" option is available on client SKUs.