Just downloaded first three samples - for the fourth, I would have to create an acount with Google. Also just installed ABX comparator in foobar 2000.
I have to learn to use the ABX comparator properly for blind testing etc ( ANYTHING but computer geek myself ) - but the first thing that comes to mind is that one track sounds mellow and the other sharp - depending how you queue them in test. They also differ in appearent loudness - the sharper is a bit louder than the mellow one. Or something in this direction. I will listen more properly after I figure out how to use ABX properly - but the differences among first three tracks is clearly audible to me.
I listened with JVC HA-S500 headphones.
I will double check the sharing permission on that last file. The abx in foobar is pretty easy once you know how to do it. Maybe i can do a quick walk through on using it