Playing USB media on Pioneer 5020FD

[wozman]

Was wondering (being a fellow Pioneer owner) if you could help me out. My current setup has the following.

Plasma TV - Pioneer Kuro 5020FD
Cable Box - Scientific Atlantis SA8300HD PVR
Blu-Ray Player - Sony BDP-S350
Receiver - Yamaha 6160B
Speakers - Bose Acoustimas 6 Speaker System
Remote - Harmony One

I have it setup the following, (easy)
Rogers Cable TV Box - HDMI to Receiver IN
Sony Blu Ray Player - HDMI to Receiver IN
And then HDMI-OUT to the Pioneer 5020FD, everything works great, with the receiver sound ect...thru the Bose Speakers, HOWEVER major hiccup. When I pop in a USB stick to the Kuro USB slot I see all the media (MP3 Files) and they start playing on the screen, but there is no sound? Maybe the Kuro is thinking to use the TV Speaker, which I dont have setup, What do I have to do, in-order for it to send the sound to my Bose Speakers thru the Yamaha Receiver. Wouldn't mind putting on a few tunes and let it roll.....

Any info greatly appreciated.....

Thanks again