Originally Posted by sanderdvd
why do I get better results with HDMI on my receiver? Isn t it so that the decoding is done in the player and that than, just like with anolog outputs, the only thing a receiver can do is amplify?
By "results" I meant the overall sound. Whether done in the player or receiver, the decoding itself will be the same (decoding = decompressing or unpacking the data). However, decoding is just one part of what makes up the overall sound you hear.
Receivers do more than just amplify the signal. They can do bass management, time alignment, surround processing, room correction. Each one of these contributes to the final sound that reaches your ears. Some of these, like bass management and time alignment, can be set on the player (though receivers usually have finer settings). But surround processing (which converts 5.1 to 7.1) or room correction (which minimizes the room's unwanted contributions to the sound) isn't found on players.
In order to take advantage of these features, you need to have the signal in digital form in the receiver. This is where HDMI is useful, since it can transmit the signal digitally instead of in analogue form. This will help improve the sound that eventually reaches your ears; i.e., better results.
Maybe I m still missing something but isn t the DAC the process where the decoding of the DD+/TrueHD is done?
DACs are Digital to Analogue Converters, and they do what the name implies. The decoding process takes place much earlier.
Soundtrack are encoded for storage and transmission, using lossy compression or lossless packing. During playback, the first thing that has to be done is decoding of the signal (decompressing or unpacking the bitstream) in order to get the original soundtrack back in its original form (PCM). The same thing has always happened with regular DD and DTS signals.
Once in PCM form, you can manipulate the signal any way you want. This is when your receiver applies all its features. Only after this step are the DACs used to convert the digital signal to analogue, just before the amplification step.
My receiver has two 7.1 inputs so that shouldt be a problem
It may not be a problem, but using HDMI will provide better results (see above) and reduce cable clutter. If you connected Blu-ray and HD DVD players to your receiver using only analogue connections (8 audio and 3 component video for each player), then that would mean 22 cables total. As menmoch mentioned, wouldn't it be cheaper and easier for you to use just one cable for each player?