I use LameXP on Windows so I cant comment on the quality of the mp3s from iTunes. However, iTunes did get a lot of criticism years ago for the poor quality of the mp3s it produced.
After some sniffing around I've found the source of this:
"There has been some criticism of the quality of Apple's MP3
variable bitrate encoding. In a January 2004
double-blind public participated in a
codec listening test of six MP3 encoders encoding at 128 kbit/s, conducted by Roberto Amorim, and the iTunes MP3 VBR encoder came last. The author has later acknowledged that there may have been serious issues with how iTunes was tested." Unfortunately the link to the tests is now dead.
A second wave of tests was done in October 2008 and iTunes fared very well:
http://listening-tests.hydrogenaudio...-1/results.htm
The results show that over 14 tests, iTunes scored 0.02 out of 5.00 less than LAME 3.97. The encoding of iTunes has become something of an urban myth and it cant be that bad after all.
If you DO want to use LAME with iTunes on a Mac, you can always try iTunes-LAME from
http://blacktree.com/
Do you have personal bad experiences with iTunes@192?