Potentially Important Discovery

[apollolux]

It probably depends on the speakers and/or source device/software. When I play a song on my iPod, for example, that has discrete channels (e.g. a particular riff only plays on the left and a separate riff plays on the right) the channels stay separate and it is clearly reflected in the respective side of the headphones/earbuds/etc. When I mix digital audio in a DAW like Cakewalk Sonar or Ableton Live I clearly hear left channels on the left speaker and right channels on the right.

Unless explicitly stated expect stereo data to be sent through 3.5mm as stereo rather than mixed down; any claim to the contrary sounds like FUD otherwise.