Running a stereo signal upmixed to 4 channels via Creative CMSS.
Vast huge immense rediculous 3D soundstage. Booming thunderous .1 channel calibre bass delivery, which reaches wind impact levels on certain tracks (the surrounder has a seperate control for bass level) Mainly from the side and rear drivers and ports.
Clean clear mids and highs, from the front mounted drivers, not going to win any prizes for detail or intricacy or resolution, but more than capable enough to provide clean good sound.
Very very good fun to use and hear.
When used with 5.1 DVD-Audio discs, crushes the dolby headphone stereo version of the experience, but falls short of a well configured 5.1 speaker setup, better than that speaker set up if you are not centrally seated as the surrounder puts you in that seat perminantly.
For DVD movies my persoanl preference is for dolby headphoen stereo, but not for any sonic reason, its because I cant kick back into my movie watching pose with the thing on.
For what I paid, Id buy a second one, but I got a steal buy on ebay.de and mien didnt come with the original box or the processor unit. Sennheiser.com were kind enough to send me a PDF of the manual.
Maybe ill do a full up review of it in the future. Ive never actually tried to benchmark it.
Also, people love it with its wacky fun crazyness.