As usual, I'm chiming in comments after the thread is done.
First, I agree that the Sonic Voom is the simplest and cheapest way to deal with the AC3 channels if you don't have an audio system that does it.
Some people complain that by using the Sonic Voom that you lose dialog that often is found in the center channel. Occasionally, I've run into programs that have the dialog volume low compared to background noise, but it's usually not a big problem.
Besides having 2 Sonic Vooms, I also have 2 Soundblaster Extigys, which are external sound cards that don't need to be connected to a computer. I used the Extigys for years for AC3, and they worked fine, except that every time there was a power outage, the volume would get turned down to zero. The Extigys, however cost considerably more than the Sonic Vooms, so although the Extigys are more capable with their sound card capabilities, the Sonic Voom wins with respect to simplicity and cost if AC3 decoding is all you want.
My big confusion though is what's the deal with the darn Fortec Mercury SPDIF output and the Extigy? Ie I have Fortec Lifetime and Ultra receivers, and the AC3 works fine through the Extigy, however the Fortec Mercury just does not work with the Extigy. It works fine with the Sonic Voom, however. If I look at the AC3 signal with a scope, comparing the Ultra to the Mercury, I see very little difference, maybe some small level shift, but nothing significant. And the NON-AC3 digital does work fine. There is something weird going on with the Mercury AC3 output. Fortec says that there is no processing and that there should be no difference. Anyway, I don't use the Mercury much anymore, so it isn't a big deal, but in case anyone uses a Mercury and is considering using an Extigy with it, there is a good chance that it won't work.
