"Harry Lavo" wrote in message
news:KvA0c.152472$jk2.593654@attbi_s53...
*snip*

Michael, I and others have described similar tests here under similar
conditions, and have always been told we are just imagining the
differences
based on "expectation bias". Expectant of what they can't say.

Harry, you know the answer to this question, as it's been repeated ad
nauseum. Expectant that the amps in question sound different.

Unfortunately, some of the members of this forum, while intellectually
understanding it, have a difficult time differentiating between "sight
*may*
provide a bias that overrides true differences" with "sight *always*
overrides true differences and makes your comparison invalid".

If you allow for the fact that sight *may* provide a bias that overrides
true differences than you must control for it, always. Failure to do so
leaves open the possibility that you may have been influenced by sighted
bias. There would simply be no way to know whether the listening results
were valid or bias influenced, and no amount of arm waving shouting "DON'T
TELL ME WHAT I HEARD" will change that fact. Bias controls are necessary
not because the biases always exist, but exactly because they may exist.