To be honest, the easier solution would be to connect your speakers to the audio-out on your TV. That way you could avoid sync issues with the sound coming out of the TV. The audio stream going over the HDMI cable isn't guaranteed to come out of the speakers in sync with what's coming out of another audio device. Besides, that way you're not giving your system more work to do by driving two audio devices (although it probably wouldn't be much).
Ehh it's alright. I didn't think the Speakers had enough power, so I was going to supplement them. However I just found out that you can hear them all the way across the house.
