Just buy the cheapest, I mean if it's the same master it wouldn't make any difference, if space is a problem for you you can always downsample it.
The k812 is a great resolving headphone to test out sampling theories. I'd recommend he get a couple of 24/96 or 192 albums, down sample some copies to 16/44 and let them decide if it makes a difference (it doesn't as far as I'm concerned).