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.

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?

In principle, yes, although the definition of what is required would
probably have to be broader than a 'filter'. In practice, difficult, as a
number of properties may be involved. Some may not be correctly
identified,
and others may depend upon the conditions of use.

Accepted. I use the term "filter" for simplicity but, I'd imagine that you'd
have to measure more than just the amp's frequency response. It would have
to be a "filter" constructed on the amp's performance at a given time - say
when the amp was perceived to be operating at its best.

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

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

Can't say as it would presumably depend upon how well the "filter"
actually
represents the totality of the processes the Alchemist is performing.

What you *could* do, though is something like the following.

Play music through the Alchemist into a pair of speakers. While doing so,
connect leads to the speaker terminals and record the signals there onto
CD-R using a reasonably quality recorder. Note the signal level with a
meter.

The replay the recorded version of the signals using a different amp that
is known to have a flat response, low distortion, and low output
impedance,
adjusing the level at the speakers to be as before. Then judge how similar
it sounds.

Repeat this process, but reversing the positions of the amps. Or using one
of them 'twice'. Compare, contrast, discuss. :-)

Alternatively, it would be possible in principle to do a 'live' version of
the above and avoid recording, although this would be more complex to set
up. Might make it easier to do a 'blind' check, though...

I would be happy to try something like this blind. I'd be really curious to
see if such "filters" were possible and whether I would be able to tell
differences, or recognise my favourites as superior to those which I'd
previously rejected.

Presumably the playback equipment would have to be that which is considered
as "straight-line" - the CD player and amp? But is there a danger of a
cumulative effect? If I use the same speakers in replaying the signal as
it's been recorded from the system, would the effects of the speaker's
balance not be duplicated? Would this be cumulative? Presumably, any small
deviance from "straight-line" in the CD or amp's replay would undermine such
an experiment.

Many of you chaps believe that the Peter Walker(?) "straight-wire" ideal is
that which any "hifi" designer should aspire to construct.

Do you think that this is attainable?

Slainte,

Jim

Cheers!