I like the vnophones vst-plugin very much, its quite subtle.
So, if i understand correctly, the first setting (%) change the angle, where the sound is coming from, right? When used alone, it only mixes left and right channel, making the sound just more towards mono. The second setting (0.00ms) controls the delay sound reaches your ear, right? When these two settings are used together, it will make the soundstage more natural and out of the head, instead of just mixing the channels together?
Even little change in the delay seems to have a large effect on the sound, specially where its coming from. Still, the effect on the soundquality/details is very little, not much coloring. I've liked the settings: ~20%, ~1ms and pretty much the default setting ~30%, ~2ms. Definitely needs to be individually configured to get the best results.
Then again, this kind of thing(configuring the settings) can get very stressing and become the point itself, instead of enjoying the music/audio. That is the dark side of the headphone listening; the unnatural stereo seperation, when listening audio mixed for the speaker listening and the need to fight this somehow.