... none of the SD receivers will decode Dolby, they'll just pass it through to your decoder...
... and all of the HD receivers will decode the Dolby.
Maybe not a 100% guarantee answer, but pretty close.
I use a set of these.
[ame="http://www.amazon.com/Cyberhome-CH-SRD-600R-6-channel-Headphones/dp/B0006688ZC"]Amazon.com: Cyberhome CH-SRD 600R 6-channel Surround Headphones with Game Decoder: Electronics@@AMEPARAM@@http://ecx.images-amazon.com/images/I/31s7uUYDl8L.@@AMEPARAM@@31s7uUYDl8L[/ame]
Works pretty good. I didn't pay that much for them. I heard about them here on Sat guys. I use the optical output on the Traxis 3500 to input to the decoder. Instead of headphones I run the output to the AUX input on my stereo amp. When I want to listen to AC3 I just switch the amp to AUX.
Think I paid around $30 for my set.
I know others have their favorites, but I've stayed away from the HD receivers so far.
Most are quite limited.
However, they do some of the necessary things, so they're sure better than nothing.
If you're looking to the future, read the AZbox review in our Equipment Review department.
One source is on eBay, and for about $100 less than GoFastMotorSports.
I've almost given in and ordered one - it's a hell of a media player.
Ask me again this weekend.