Class A, B, C? What do they mean?

http://forum.audiogon.com/cgi-bin/fr_srch.pl?&1&procsrch&3&4&

The first five or six hits cover you question in various ways. Search "class" in the archives if the above doesn't work.

A few other good posts are:

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1024059614&read&keyw&zzclass=a

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1020620795&read&keyw&zzclass=a

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1019521148&read&keyw&zzclass=a

Just highlight each of these in turn and copy them to the Address bar above. They are some nice past threads on the topic.

I often read "Stereophile class A" amp. It seems Stereophile class A is not the same as "class A bias" amp.

What does "Stereophile Class A" mean for a piece of an equipment?

It's supposed to mean that the equipment reproduces music exceptionally well. The jury is out on that since it might mean that the company advertises in Stereophile exceptionally often.