Oh! That one.
hafler_AVR6000.pdf
click on the PDF file when the site opens.
Edited:
It appears that the only output other than speakers at 600 ohms each is the REC out (Record Out). Unfortunately I'm thinking that this is going to be a fixed ouput and may not carry enough volume to power a set of headphones or other speaker. You would have to run it through an amplifier, and one that has the output that you want.
I'm also thinking that the simplest solution is to go buy an inexpensive "home theater" unit at your local Wally-world. Anywhere from $80-Lots of $$, your choice.
Good luck