Note from admin: Split from this thread --JBI
It doesn't work that way. Simple tests can be done that completely throw out the whole notion of your computer simply outputting a pure sound. Adjusting volume on a digital stream itself is processing. How a sound card and its drivers decide how to change the volume levels itself is processing. Upmixing from a stereo output to surround sound is processing. Going from surround sound with 7.1 or 5.1 to headphones is processing.
IF a computer functioned as pass through without any adjustments to the sound stream all sound cards would sound identical. But you can even get modified versions of Creative drivers that make things sound different (not an adjusted EQ). How the sound card interprets and decides to output content is processing in and of itself and they all aren't the same. I went out of my way to test that and even wrote about those experiences in the Titanium HD thread.
Drivers are software, they also determine how computer hardware is used. It's entirely possible for drivers to process some of the above in hardware. It doesn't need EAX or OpenAL. Nvidia and AMD do the same exact thing. There is more then one layer to software.
It is entirely possible to do direct output for a DVD or such with the help of codecs like AC3filter, which allows you to setup a passthrough, but in a computers native condition it does not function simply as a passthrough for sound.