Brucest wrote:

Many recommend power conditioning. Manufacturers seem to emphasize how effective their products are in cleaning up line power. This can be easily measured so I'm sure they're right. However, that seems to be a bit beside the point.

The correct focus is what impact does the conditioning have on audio equipment output. Measure say an amp with and without power conditioning and report on the differences. Again this would be seemingly and easy measure and would tell us what we're getting for our conditioning $.

Power amplifiers generally do not benefit from being connected through a power conditioner. Their input and output levels make them relatively insensitive to this kind of problem, and in any case their own power supply circuits do a very good job of filtering out any nasties.

Other audio componenents may be helped by a good power conditioner, IF the local power source is relatively "dirty".

Brucest wrote:

But benefits are claimed for all equipment, and measuring the resulting improvement in performance of particular items benefiting from the conditioning would seem to be the proof of the pudding.

Claimed by who?

Measured how and by who?

Under what specified conditions?

This reminds me of someone who is convinced that his soul needs to be "saved' and goes to a tent revival meeting.

Bless you...