[PROBLEM] No Dolby Digital (AC3) audio?

[rikardo1979]

does your TV decode AC3 from HDMI and out it to Coax ? just leave XBMC Audio out on 5.1 and external decoders enabled. Than see if you have sound from your TV speakers, it should downmix and play from TV speakers
edit: if this does work and you still have no sound from your amp connected over Coax than its more likely that your TV somehow either does not support this so its not able to out sound from HDMI to Coax or the decoding doesnt work for some reason