I don't know but Bill McClain's site lists mkv as supported, and he's pretty sharp. Last I heard there were some problems with it after a firmware change but that's all I know. See my earlier post for link to his FAQ for the 103
I bought the Android app BubbleUpNp but it's only got me confused. I couldn't get any sound from it and switched back to the network function on the Oppo. I'm a little weary of it all right now, got some severe pain issues that is distracting me so I let it go for the moment.