Ok, that's pretty much what I thought. Thanks for the detailed answer.
What about if I have a 192 mp3 and convert it down to 128? I would have to have some pretty high end equipment to even tell the difference, right?
It depends on how sensitive you are to sound.
Some people are so tone deaf they cant tell the difference in stereo and mono.
I see no reason to convert down to 128 unless you are having storage issues.
My GF cant tell the difference in the sound coming out of my $50 headphones vs my $1500 headphones.
It blows my mind.
So to answer your question I have no idea if you will be able to tell the difference.
But I would be able to tell.
It would go from bad to worse.