Sony BDP-S7200 and DSD-streaming

[dvdr]

Hi,
just got the new Sony BDP-S7200, a upnp-ready BluRay-player which is able to play dsf and dff-files natively, when provided via USB.
What I am trying to achieve is to play them via Minimserver, which I am not able to do...

The following setup with the following options is available:
- BDP-S7200: provides audio out via HDMI: either conversion to PCM or output DSD natively
- Preamp Onkyo PR-SC5508: accepts both PCM as well as DSD via HDMI, is able to decode DSD
- installed Minimserver 0.8-31 and Minimstreamer 0.4
- I can access Minimserver:
a.) either directly from within the Sony's menu (like a Playstation, there is a graphical menu: Music->upnp-servers (in this case Minimserver)->browse to the track, add it to the playlist
b.) through Plugplayer or Songbook, choosing the Sony as a renderer

As stated before, the Sony accepts dsf and dff via an USB-stick and plays them - both conversion to PCM or native DSD output via HDMI to the Onkyo preamp works. The Onkyo's input monitor shows PCM or DSD respectively.

When switching over to upnp, though, nothing gives playback:
- Browsing upnp/Minimserver via Sony's own menu: playback of all file-types, even highres flac, works. When it comes to the indexed dsf/dff-files, I can get as far as the album, but then: "no playable content".
- switching Minimstreamer to "dsf:dopwav, dff:dopwav", I can browse into the album, and DO see both the dsf and the dff file, and can add them to playback, and on the Sony's monitor screen, I can see the file "playing".
On the Sony's Monitor, I can see "LPCM 8.5Mbit/s", and the Onkyo shows me PCM 2.0 Channels, 176.4kHz - but no sound... So I assume, the Onkyo refrains from playback, because it "sees" a PCM-file, which it does not decode, because it does not activate DSD-decoding.

Very same applies, when I try to do the playback via Plugplayer. I can select the Sony as the renderer, but that's all. No sound, either.

Is there any way to get playback working?
Thanks in advance for your help.