Pure 2.0.
Dun mo maeexperience ang galing ng system mo, if you can able to determine the separation of instruments, soundstage, and how the music envelopes you, As long as you're sitting in a stereo system's "sweet spot," you'll be hard-pressed to even point out the speakers' locations.
My opinion is if it's a two-channel recording then listen in two-channel. If it's a 5.1 surround recording, listen in 5.1 surround.