This isn't about the portamento anymore, but I just played a bar in F minor and listen to that high F how there are really ugly high frequencies in the sample:
http://www.hanshafner.de/quickupload/appassionata_pheep.m4a
Cheers
Hans
http://www.hanshafner.de/quickupload/appassionata_pheep.m4a
Cheers
Hans