The whole out of your head speaker like soundstaging thing everyone talks about, do you need surround sound processing or binaural recording to hear that? Sorry, never had an open back before so I don't know and I would hope I can at least get somewhat of the effect without needing extra equipment/software or special binaural recordings.
I plan to eventually get an extrernal surround processor/sound card for my ma900 anyways but not right away as I don't have money for it atm so also if anyone can recommend a cheap external surround processor or sound card that works well with ma900?
You don't need any special recordings, however the type of music you listen too will matter. If you listen to top 40 stuff, there is not much sound stage anyway. If you listen to an orchestra, the high quality 320k files that are on Google Music Play will work.
Of course, as you get better recordings and better dac/amps, this effect is magnified, but with just a computer, you will notice a difference.
Oh, and no surround sound processing.