MC has three delivery modes a) native (not transcoded), b) transcoded to PCM (WAV), or c) transcoded to L16 (another flavor of PCM).
If your MinimServer succeeds in pushing native AIFF files to your Chord, then it should also succeed if MC pushes the same file in native form. After all, it is the exact same file being pushed to the same renderer in both cases. There is no reason why it should fail.
If on the other hand your MinimServer is converting the native AIFF from (say) AIFF/88200/24 down to (say) AIFF/44100/16 then there could be a reason why the one server succeeds and the other fails. What is the format of your AIFF original files?
{ PS I know very well that what Squeezebox did with its transcoding was far less transparent than what happens inside UPnP (read my sig) -- so let us not even start down that road.. }