If you look at this link to the Sony BDP-S590 you will see a new option to Directly access files on your PC.

http://www.sony.co.uk/product/blu-ra...layer/bdp-s590

I assumed the player would now be able to access SMB shares via a UNC path and bought one.
However, in the device there doesn't appear to be this capability (that I can see) and I know see from the technical specs that it now reads as "DLNA Direct PC File Access".

This would suggest that the player can use DLNA without the need for transcoding for a considerable range of files.
However, I switched transcoding off in Mezzmo and I couldn't play one of my MKVs and I also couldn't play a .M4A AAC music file.

I've used Mezzmo for a long time and I wonder if anyone on the forums has any ideas about these advertised features from Sony.

Any info would be much appreciated.

I attach the getprotocolinfo from Intel Device Spy if that is useful for anyone.
Sony BDP-S590 InvokeProtocolinfo.txt