If I'm following this discussion subject correctly, I believe the potential problem relates to when the Realiser is used as part of an "HDMI relay" passing on video via its HDMI output to an HDTV display. HDMI handshaking is notoriously delicate when more than two devices are involved in an HDMI chain, insofar as how the initial source device will deliver its audio. Whether or not the end-device's (i.e. HDTV) audio capabilities determine what the initial source device delivers, or whether the intermediate-device's (i.e. AVR, which is the first device connected via HDMI to the initial source device) capabilities control... this is not always a constant. It's further complicated by possible "HDMI audio" settings in the source device, which are there to potentially overcome such complications and actually force audio delivery over HDMI to be a specific type.
For example, in my Yamaha RX-V863, if I set its HDMI audio to "pass-through", that apparently implies it is the end-device (i.e. HDTV) which drives what the source device (e.g. DVR) will deliver. And since the HDTV can only accept 2.0, that's what the DVR delivers over HDMI to the AVR. If "pass-through" is disabled, then it is the capability of the AVR itself (which obviously CAN accept multi-channel) which tells the DVR to deliver DD5.1 over HDMI. So obviously I have "pass-through" disabled on my AVR. Also, that is also why if DD5.1 is the source audio you might as well use an optical connection from source device to AVR... since optical is NOT impacted by an HDMI handshake, and will ALWAYS deliver multi-channel from source device to the AVR.
That is why I have just upgraded my V863 (which has only one HDMI output) to a V867 (which has two HDMI outputs), as part of my upgrade from analog Realiser to HDMI realiser. One HDMI output from the AVR will go to the Realiser (and no further HDMI connection from the Realiser's HDMI output), and the second HDMI output from the AVR will go directly to the HDTV. My Oppo BluRay player will do its own decoding to LPCM to feed the AVR via HDMI and then on to the Realiser via HDMI. My DVR will feed undecoded DD5.1 to the AVR (also via HDMI) which will then decode and feed discrete channel preamp-out analog to the Realiser via RCA analog. I will simply switch Realiser inputs when watching BluRay movies with lossless DTS-HDMA vs. when watching HDTV from the DVR.
I had no desire to use the Realiser's HDMI-output to relay video to the HDTV, not only because of the potential for audio-over-HDMI problems, but also because I use the Realiser in analog-bypass mode (i.e. Realiser powered off) when listening through my 2.1 speakers so I still need to get video to the HDTV, which will not happen if the Realiser is powered off (when using the HDMI-relay output of the Realiser). That's why I had to upgrade to a 2-HDMI-output AVR as part of the HDMI Realiser acquisition.