EVA700 No Stereo Music Output to HiFi

[Tecno]

I am using the EVA700 with Twonkymedia connected by PAL SCART into a Pioneer Plasma Flatscreen box. When playing music [AAC files] I am receiving stereo sound through the flatscreen speakers. However when this signal is sent via audio leads from the flatscreen box to an AV HiFi amp I am only receiving one sound channel. When TV sound is sent through the same leads stereo is received.
EVA700 audio setup is for Stereo and PCM.
Any ideas?
Also how do you get music to play at the same time as showing pictures?