JustMe wrote:

In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I would
assume, judge just what it is about one amp that might make it preferable to
another amp, to some listeners.

Correct.

Would it therefore be possible for someone to take a "straight-line" amp -
and I'm happy to accept whatever you judge to be a representation of the
closest example of this - and then build an add on "filter" to alter its
sound to reproduce the sound quality of the Alchemist?

yes.

Then, maybe, a dozen or so other popular amps could be measured, and filters
built to represent each amp in turn.

You could do this.

Would I be able to hear the difference between the "straight-line" amp with
the Alchemist filter and the Alchemist amp?

Assuming the alchemist distorts in some way (you say that it makes an
audible difference elsewhere, so I assume it does), yes.