I did try this with headset and in my room with my new AV7706 pre-pro 5.1.4 setup.
The headset experience is like an upscale version of Dolby Pro-Logic since the sound source is still 2 speakers (L and R)
The in room with 5.1.4 speakers, there are clear distinct source of sound for the 9 speakers.
The "impression" is cool on some music ; it sounds like you are in the middle, the selective details of instrument, or note or voice can move from each speakers or come all at once from all speakers. So whether you like it depends on your taste of the artist/mastering mix the sounds.
On older song that was recorded in studio or classical song that was recorded life in auditorium with stereo microphones. The Stereo mode is better to RECREATE the original imaging SOUNDSTAGE (can hear the position of the singer, drum, piano, guitar) more accurately.
For example on Norah Jones Album, they remix it for Atmos and it sounds interesting.
But you can still pick the single song in stereo mode to play it with just two speaker stereo.
For this Album, I prefer listening with just two speakers stereo via SACD.
