How to clone audio output?

Solution 1:

Your fears are founded : rear and front output are the same only when the source is simple stereo (i.e. music, or basic divx films). For other sources (DVDs, but most importantly games), they are different, and you will have a bad experience...

I Have the same kind of setup as you, but with two sets of speakers and a headset. The only solution I've used so far is use only the front output, with an audio "strip". That is crude, but works...

I'm looking for alternatives, but haven't found yet...

Solution 2:

I think that in general they are the same, unless and application chooses to use the differently.

Example: application playing stereo audio: both front and back are the same Example 2: application playing movie with surround sound: front and back are different

Again, this is just my experience with the computers I've owned. It may differ with you computer.

Solution 3:

What you want can be done if you don't mind getting your hands a bit dirty:
You need to write a small config file (.asoundrc) for your ALSA-sounddriver.

I can't give you the magic formula because it is very dependent on hardware configuration.
There is, however, extensive documentation about how to do it
See the links for documentation:

http://alsa.opensrc.org/.asoundrc
http://www.alsa-project.org/main/index.php/Asoundrc