Is it not possible to have the format determined by the renderer and if two or more are selected then each gets its own format requirement?
The Upnp specifications for digital media renderer and digital media server have a method called GetProtocolInfo that allows each device to publish a list of all the different media formats that it is capable of delivering (server) or consuming (player). And the intent of the specification is that for each track being played, the server shall dynamically select the highest common denominator between the format of the actual track and the respective source- and sink- protocolinfo formats of the server and the player.
Unfortunately MC does not follow the intent of the specification, insofar as it only offers a fixed choice between native and one other fixed choice of transcoded format (actually one fixed choice each for audio, video and images).
I have been lobbying JRiver for some time to change this, and implement a proper Upnp /Dlna "auto" setting as the specification intends, but so far they have not committed to do so.