QuestionCan this be done?
AnswerYes. It is not easy, however.
My question is why would you want to?
Actually, for the cost of adding the headphone feature you could purchase another player (cd or dvd or receiver/tuner) that DOES have the headphone output built in.
Back to your question: There are two ways of doing it that seem reasonable.
ONE: Build it inside the unit. Hire an engineer who can study the circuitry (which is always non-standard with Bose) and add the extra connections and headphone amp inside.
TWO: Purchase an external stand alone headphone amp box for this purpose. Or build your own.
http://www.headwize.com/projects/showfile.php?file=cmoy2_prj.htm
And other such boxes that you can purchase or find on eBay and other auction sites.
If you have the 5.1 playback system (there are several versions of the 3.2.1 Bose) and it does not have stereo conversion you may need a 5.1 to stereo converter in addition to the headphone amp (for stereo listening). There are 5.1 headphone devices but they are rather esoteric.
See this discussion about surround headphone listening:
http://www.audioholics.com/reviews/speakers/headphones/ltb-audio-ac3amp5-1/5-1-h...
You can do your own googling and find many other articles and products that may fit your interests.
Happy Hunting.
C
