Precision M4800 HDMI no audio - share your experience

Hi all Precision M4800 owners,

I'm looking for anyone who can share their experience with hooking this machine up to a TV over HDMI: are you able to transmit audio?

I have an issue with mine where the system does not recognize that it is connected to an audio-capable device over HDMI (screenshot is with a device attached and displaying):

I've gone through the Dell drivers, drivers from Nvidia's site, A13 and A14 BIOSes and everything in the HDMI Audio FAQ that looked remotely relevant, as well as a discussion with Dell email support and got nowhere.  After some time, I got a DisplayPort to HDMI adapter and now I have audio through the DP so the core problem has been worked around.  With the DP adapter, Port 0 shows as connected and lists the TV.  The problem, I believe, lies with the ports being treated as something they aren't:

The laptop has one DisplayPort, HDMI, VGA and the internal display, it doesn't have a second DisplayPort nor DVI output.  The TV on HDMI seems to be treated as DVI, which doesn't support audio, so I guess it never seems to try sending it.

I'd like to get some corroborating evidence for a case to update the BIOS (where I think the problem lies, at least) so that I can use my HDMI port as an HDMI port. The most important data will be from anyone else using one of these machines that was made with the QHD (3840x2160) display, not the FHD (1920x1080) one.  The QHD display uses the Nvidia chip for everything and the Intel IGP is disabled; most Dells run HDMI audio through the Intel chip which I why I think this one fell through the cracks.