Why not just install a DLNA server? Then you can access content on your PC from the devices themselves. Good free ones are PS3 Media Sever, Serviio and Plex.
This reg tweak might work:
Code:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\.flac]
@="[ProgID]"
"Content Type"="audio/flac"
"PerceivedType"="audio"
[HKEY_CLASSES_ROOT\[ProgID]\shellex\ContextMenuHandlers\PlayTo]
@="{7AD84985-87B4-4a16-BE58-8B72A5B390F7}"
Replace [ProgID] with the appropriate value of your current file association.
Windows will do (poor quality) transcoding for non-native formats.