Originally Posted by Radioking59
Wouldn't this require computer playback or a special receiver? So unless you have the SACDs ripped with a PS3 or a DSD receiver with Dolby headphone, I don't see how this would work.
Pretty much. Or if you can get a line output for each channel, of course it is possible to process it with the right transformations to get the desired effect (either doing the HRTFs in hardware, or more likely, doing another A/D -> processing in digital -> D/A).
Originally Posted by bigshot
Do multichannel simulators take multichannel input, or do they only create their own ambiences?
Dolby Headphone can take 5.1 input.
There are plenty of surround sound downmix options for headphone (and even stereo speakers) playback, so you can at least use the information in the extra channels in some way when playing back a surround sound source like a movie. It's been a while, but I tried the ffdshow audio filters stereo -> headphones, and that sounded not so good compared to just playing back the original stereo on headphones, but with a surround sound source the 5.1 -> headphones sounded okay and to me was better than just taking the stereo channels.
Conceptually, you're just looking at mapping X inputs (one for each channel source, corresponding to each speaker and its location for a surround sound setup) to Y outputs (one for each speaker or headphone transducer). There is a transfer function for each input to each output. At each output, sum the corresponding parts from each input and play that back. You can use whatever transfer function you want, whatever number of inputs and outputs: 2 inputs to 2 outputs type of crossfeed for converting normal stereo speakers positioning for headphone playback, 5.1 inputs to left/center/right speakers, and so on. It's just that the "correct" transfer function depends on the input's intended speaker positions and your output speaker/headphone positions (and also your head/ear/torso/etc. shape).
Edited by mikeaj - 10/30/12 at 1:16pm