More detailed info, courtesy of crutchfield.com
Overview: The SU-DH1 is a portable surround sound headphone adapter. It features Dolby headphone technology to provide 5.1ch surround sound through any set of headphones. It comes with an analog input cord that can be stored into the unit, and also has an optical digital mini jack. Ideal to use with laptop computer, portable DVD player, handheld video viewer, and portable game systems or other portable music/video product. Also it can be used to enjoy the in-flight movie with surround sound. Carrying pouch, airplane plug adapter, and two AA battery are all provided.
Virtual Surround Sound Modes: The SU-DH1 can reproduce the following formats:
* Dolby Digital: This is used to reproduce multi-channel soundtracks of the software encoded with Dolby Digital.
* Dolby Digital Pro Logic II: This is a newly developed multi-channel playback format to decode all 2 channel sources (stereo source and Dolby Surround encoded sources) into a 5.1 channel. There are two modes of Dolby Pro Logic II:
o Movie: suitable for reproduction of the software encoded with Dolby surround
o Music: suitable for reproduction of any 2 channel stereo music sources
* DTS Digital Surround: This is used to reproduce multi-channel soundtracks of the software encoded with DTS digital surround. DTS surround is another discrete multi-channel digital audio format available on CD and DVD software.
* MPEG-2 AAC: This is a surround format developed by MPEG and can reproduce the sound in 5.1 channel at the maximum.
Surround Functions: On the face of the SU-DH1, there are two buttons, one is labeled "Dolby Pro Logic II" and the other is "Dolby Headphone." These buttons allow you to choose the particular playback modes. You can choose from the following modes:
* Dolby Pro Logic II: Auto, Movie, Music, Off
* Dolby Headphone: DH1, DH2, DH3, Off
Line Attenuation Switch (LINE IN ATT): This switch allows you to adjust the input volume level of the component connected by line in cord. Set the switch to -8db in standard use. When the volume level of the component connected has a low signal set the switch to 0 dB. The switch is found on the right side of the adapter.
* Right side of the adapter
o Mini-jack female Digital input
o Mini-jack female Headphone output
* Bottom right side of the adapter
o Mini-jack male Line input on a 4.5" cable