Harry Lavo writes:
"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

...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.

I don't understand why you come to that conclusion. Surely this
"irritation" could be caused by all manner of things. Perhaps you
subconsciously don't like the colour of the front panel, or the name
of the manufacturer. Who knows?

If I had the experience you have described, I'd have to admit that I
didn't know what the source of the problem was. But you conclude it's
definitely something to do with your perception of the sound of that
particular amplifier.

Andrew.