Rear panel space is gong to be an issue, maybe the L4 version will have only a couple SPDIF inputs and an output - the rest dedicated to the USB / MicroSOM ports :-
2x USB "A" (Host)
1x RJ45
HDMI
SD Card Slot
Maybe WiFi Antenna (I'm not sure if we will include internal WiFi, depends on screening and emission)
Power connector for the MicroSOM section
----------------------
USB 2.0 "B" port (for USB audio streaming).
Clock-Lock Optical Output
Optical SPDIF Output
Coax SPDIF input
Optical SPDIF input
2x 3.5mm RC Bus
Hopefully I'll be able to squeeze the above onto the MDAC2's Rear Panel (Digital Board).