Something like this should work, it can pass through the HDMI and it extracts the Audio and put it to an Optical port, so should be able to get audio from both cables at the same time.
1080p 4-Port HDMI Input to HDMI + Optical/Coaxial Audio Output Converter (100~240V AC) - Free Shipping - DealExtreme
1080p 4-Port HDMI Input to HDMI + Optical/Coaxial Audio Output Converter (100~240V AC) - Free Shipping - DealExtreme
United States of America