First, I have to say that the encoder for the 128k file is surprisingly good. Things have certainly improved very considerably since the warbly sound we're used to with files compressed that much.
I loaded both tracks into iTunes + Amarra and played them through my Stax rig. The first file that I heard (I wont say which, as I'll PM the OP instead Edit: See edit below as well) was distinctly compressed, with the instruments lacking the complex harmonics that I usually expect with violins, sounding instead flat and artificial. There are a great many classical recordings that don't capture this well, and this is one of them, as when I heard the other track, I could pick these things, but only because I was paying attention.
To be sure, I duplicated the files in the playlist a few times and hit the random button without looking. I could consistently determine which I was listening to every time, soon within the first few seconds of the track starting.
That all being said, I have been a critical music listener for a couple of decades; I have a high-end rig and I'm familiar with musical instruments, so the combination of all those things made it easier. Again though, it's remarkable just how good the encoding was if that's what a 128k file sounds like now and I highly doubt I would have picked it as easily out of my iPhone or iPod, for example.
Edit: I just ran both files through an audio program to confirm that I was indeed correct, the file I picked as being compressed having a hard cut-off at 16 kHz.
Thank you for putting so eloquently into words what I felt! This for me is what I was on about with the 128k file lacking emotion and feeling.
I would love for you to listen to the tracks on the ipod. This is how I did it through my various set ups including my portable Stax rig and I did indeed hear the difference.
I have been listening again and again since writing last. I said previously that it did not lack the detail, well, especially listening with the stax that was an erroneous statement on my part and how you describe it is perfect. Thank you for having the technical vocabulary I lack!