The DSU and DTSN:X up mixers are improved over previous versions as they attempt to treat the sounds in the tracks as objects in a three dimensional space using just a 5.1 setup. The effects can be heard when switching from DD or DTS to DSU or DTSN:X but the listener will decide if it is actually an improvement to the sound.
Height virtualization is now available as well from Dolby and DTS. Some receivers have their own rear channel speaker virtualizer function. When either DSU or DTSV:X is applied, they process the signal and take whatever effects would have been up mixed into height channels and sends them to the existing speakers and attempts to make the sound appear as if it is coming from above.
Seeing what is going on by bringing up the GUI doesn’t show much when using Dolby. So, if using virtualization on a 5.1 speaker setup, using DSU or Atmos height virtualization will simply show DSU 5.1 or Atmos 5.1 as the output signal to the speakers. It’s not very descriptive of what is going on.
DTS gives a bit more information while it up mixes. So, if playing a DTSHDMA track, one can apply Virtual:X and display the process. The DTSHDMA track will be displayed, then Neural:X since it is up mixing and then Virtual:X as it takes the processed signal to the existing speakers in the setup to make them appear to come from above. DTS:X tracks skip the neural process and go straight to Virtual:X like Atmos tracks go straight to 5.1.
While Dolby removed cross up mixing limitations, many will not be able to apply DTS up mixing to dolby tracks. Converting signals to PCM from devices will result in the ability to use both up mixers but will also kill metadata from both Atmos and DTS:X and the processing of the signal will not be the same as if using the virtualization processes with the non converted tracks.
There hasn’t been near enough information put out there by Dolby, DTS or manufacturers in a way that helps people wrap their heads around what is going on.
Oh, and if you decide to play with PCM tracks back and forth, you will find DTS up mixing more aggressive and especially so when using Virtual:X