"Andrew Haley" wrote in message
...
Harry Lavo writes:

As a specific example, I recently bought a used power amp by a
manufacturer
based on my satisfaction with another piece of gear from the same range
by
that same manufactur. It was hopefully to replace a piece of gear that
I
had been relatively happy with, but I felt was slightly lacking in a
specific regard. When I got the unit, I pulled out a few "test" disks
and
substitued the units back and forth, playing and replaying sections
from the
disks. My overall evaluation was that the units sounded essentially
alike
in frequency response and speaker control, and the new unit had the
characteristic I had been looking for (also good). So I was
predisposed to
keep/like the unit. I put it in the system and used it as I worked at
the
computer for a week...but I noticed that I became tired of listening
and
slightly irritated after several hours..that had never happened with
the old
unit. Switched it back in, went another week, no problem. Put the
"new"
unit back in, another few days...same irritation problem. Back in went
the
old...no problem..and it is staying there and I am selling the new
unit. If
anything my expectation bias was that I would like the new unit, and
the
comparative testing tended to support this. But clearly long term
there is
a problem and it is a piece of gear I cannot live with.

What I can't understand is this: what leads you to believe that this
irritation had anything to do with the actual *sound* of the used
power amp? It could surely have been caused by all manner of things.


Cause and effect. When the amp played for long periods, it affected me.
Other amps do not. I've had this happen with other pieces of gear in the
past. It is not a conscious thing initially, but it is definitely related
to the reproduction of the music in some fashion.