And It really is hard to find true analogue 5.1's
Maybe because they're marketing BS which actually can't fully work as claimed?
5.1 surround sound is intended for speakers, with sound from left side speakers reaching right ear and vice versa.
While during their travel to opposing ear sound waves get delayed and also frequency response of signal changes compared to signal traveling to ear in direct path.
That's how brain deduces sound directions and also distance in real world.
In headphones that sound traveling to opposite ear doesn't happen.
So directionality won't be natural and also soundstage likely sucks.
And getting good sound from headphones requires making driver and headphone casing to work together and is always balancing between different things.
So haphazardly cramming in more even cheaper drivers never improves sound quality.
With human having only two ears/receivers two audio channels is enough for 3D sound.
It's called as binaural sound and it works really well with actually good headphones.
http://berkeleybside.com/sound-dimensions-of-binaural-recording/
Same can be simulated by taking 5.1/surround sound and processing it with correct algorithms.