Thanks for the quick reply!
The second and third codecs you linked don't include Dolby Headphone:


As for the first codec, it's called "CyberLink Audio Decoder (PDVD12)," so I'm assuming it's the right one. But when I go to "Play > Filters > CyberLink Audio Decoder (PDVD12)," this is what pops up:

It looks like adrift had a similar issue with PowerDVD10, but I'm not sure how he solved it. Something to do with CyberLink Audio Effect? Any ideas?
Thanks again =)
EDIT: Oh, apparently you have to filter the audio through CyberLink Audio Effect and select Dolby Headphone there. But for some reason Audio Effect won't let me apply any changes I make to it. I press "Apply" and nothing happens. Hm.
EDIT: Okay, I can get Audio Effect and Dolby Headphone to work, but the channel order given here apparently doesn't work with CyberLink PDVD12. I've played with it for a couple minutes and I can't find out what's wrong.
Edited by Hakuromatsu - 10/27/12 at 12:57pm
Cyberlink Audio Video Codec Pack from PowerDVD 13 Ultra
work with
Video : MPEG2 / MPEG4-H.264 / VC1
Audio : AC3, DTS 24/96, Dolby ProLogicIIx, Dolby DigitalEX, TruSurroundXT, CLMEI2, Dolby Virt-Speaker, 5.1, 7.1
Download:
http://uptobox.com/jh8j2cwxojkg