Ubuntu – Ubuntu 12.04 spdif output doesn’t support multichannel sound

I'm a relatively new Ubuntu-user, and I need a bit of help.

I just recently discovered that my laptop (an Acer Aspire 5670), has an optical-spdif output and since it's connected to a 5.1 Yamaha Receiver I bought a special optical cable and connected them properly.

Now, I noticed most people usually find at this point that they cannot configure their sound cards to output an spdif signal, but that is definitely not the problem in my case, since when I made the connection Ubuntu automatically changed the output to spdif (and properly gave me the option to choose between spdif and analog) and I could hear everything just fine (more than fine actually, since the sound was greatly improved!).

However, what did happen was that the spdif signal was set to 2 Channel Stereo and there is no option whatsoever for multichannel sound through the spdif output! (while, there is a 5.1-analogue output option, which I tried while the laptop was connected with the spdif cable and obviously nothing happened) So even though I played video files with multichannel sound (6Channel AC3 and DTS) the audio reached the receiver as 2-Channel PCM. I tried playing the files through different players (Movie Player, VLC, SMplayer) but nothing changed.

So, here's hoping someone could help me figure out whether this is a software/driver problem (and if so, how and if I could possibly fix it) or a hardware problem, for instance that, maybe, my sound card can output spdif but only for 2Ch. Audio (which would be weird but possible I guess) and in which case, I suppose, I can't do much more than accept my defeat!

Thanks in advance to anyone that answers! 🙂