I‘ve found it very effective at upmixing 5.1 music that has intimate characteristics. But it’s just to wild with pop music that has a lot of inherent ambience. Why DSU it is not adjustable is beyond me.I use DSU for up mixing 5.1 music, and I think it does a good job for that use so I get to use all my speakers.
BTW, try the stereo track One Fine Morning by Lighthouse (1971) using DSU. It’s incredible processed with this upmixer.