Upgraded to HDMI - Now having sound issues

Longtime reader here and my first post.

I usually can figure out home theater issues, but this XBox problem has me baffled.

I had been using component cables from my XBox 360 to my Sharp LCD but encountered a display "reset" every few minutes that lasted for about 3 seconds each time. I did some research and found that a HDMI cable should solve this.

Got the cable with the audio dongle in today and promptly replaced it. I have Astro headphones that plug into a mixamp with Dolby Digital via an optical cable. So I ran the HDMI to the back of my TV, used the dongle and plugged my optical cable into that and then the other end into the mixamp which my headphones plug into.

When I turned on the Xbox and popped on my headphones I had no sound - EXCEPT for chat voices (I was playing an online multiplayer game). I heard and could speak over voice chat but had absolutely no game sound. I turned off my Xbox and then back on and now have no sound at all.

Now, after some reading I've seen that there used to be a bug with the new Xbox dashboard but I thought I read that it was fixed. Any ideas? Any settings I'm missing in my Xbox? Very frustrating, to say the least.

Thanks for any help.

Unfortunately I don't have the option of going back to component/optical because of the flaw in my TV with the Xbox connected via component. But, I did find a solution (so far):

I read up on the Xbox Dongle used to hook up optical while using a HDMI cable and found that you can bypass using a dongle by prying the cover off the end of the original cable that came with the Xbox (the cable that has the optical out). [I have a link in the next post on what I'm talking about since you can't post links unless you have 3 posts or more in these forums.] After prying off the cover of the orginal Xbox Cable and plugging it in along with my HDMI cable (it's a very snug fit, even without the plastic covering, but I got it in there) it works, which leaves me two conclusions:

Either I had a faulty dongle OR the dongle just doesn't work correctly when trying to run your audio through optical and using the HDMI cable for video purposes only.


Either way, it's working well, so far.

Here is the link on how I removed the cover on my orginal Xbox Cable to allow it to fit along side my HDMI cable - http://www.chadledford.com/?p=50 .