Hi Malc, I would suggest a blind test is in order across several types of music :D
I would suggest the 128kbs tracks would have a more compressed soundstage, and lose some of the top end
clarity. Bass can also sound muddled and ill defined IMO. In a test in last months What Hi-Fi magazine, some
blind listening tests using readers as testers found people could tell the difference between 128kbs & 320kbs,
but less could tell the difference between 320kbs and some of the lossless formats (if at all).
My own personal preference is everything gets ripped & stored at 320kbs. Yes the file size is larger than 128/192/256kbs, but hard drives and personal Mp3 playes are down in price these days, so larger file storage space required
for the bigger file isn't the issue it once was. For the increase in file size to quality, it's a trade off well worth
making IMO. The difference on a good Mp3 capable Head Unit between 128kbs > CD is fairly obvious, 320kbs > CD
is really minimal.
It all depends on your ears, listening to music is a very personal matter as no matter how logical bigger is better
may sound in theory, if you can't tell the difference in a blind listening test, then go for what suits you :)