This kind of test (aka an ABX test as you no doubt know) is relatively easy to implement with little resources, esp. for an amplifier (harder for speakers where acoustically transparent screens are needed, but for amps, no problem).

It is my belief, based on lack of such evidence, that at least 90% of recently designed solid STATE amps (note the emphaisis ON recent as in last 7 -8 years or so) are sonically INDISTINGUISHABLE.
Otherwise, given the burning interst on such subjects on other fora such as the taco bell forum, no doubt such findins would have been broadcast from the rooftops.

Again, it would be good if someone like Earl weighed in here, since he spends a lot more time thinking about these issues, and this is a profession for him, versus a hobby for me.
-akhilesh

1. A thought experiment: Suppose you were a subject in an experiment. You were asked to listen to a signal, that was emanated from an analog transducer (a speaker). THis signal (program material of some sort) obviously was repreented by a certain waveform. Let us call this waveform S1.

S2: Now let us suppose the same signal was slightly altered, so that the 15000-20000 Hz components in the waveform were increased by 0.3 db. Do you think you could distinguish S2 from S1. Clearly, measuring instruments could, but could a human being? The answer is no.

S3: NOw suppose we took S1 again and this time increased the distortion in the signal by 0.01%. Do you think you could distinguish S3 from S1, or for that matter from S2? THe answer is NO, again.

Most solid state amps available today of almost any price over say $200, differ only in thses levels of magnbitude, on the frequency curve & distortion.

Now, why shold we buy mor eexpensive amps then? Is this bad news for anyone?
The answer is no, for several reasons:
1. More expenesive amps may have more extended operating characteristics. For example, a speaker may go as low as 1 ohm on certain frequencies, and a cheaper amp may not work there.
2. You can buy a ferrari for $250,000 or a porsche for $90,000, ith the porsche having better accelration, stopping, skidpad & overall performance than the ferrari. Do you think Ferrari should shut down? No. Many people would choose the ferrari for the name, the way it makes them feel, and the way it looks.
A lot of audio jewellery is sold for these reasons as well.

The problem occurs when certain unscrupulous manufacturers, magazines & reviewers perpetuate a myth that the more expensive amps have to SOUND better, and try to convince listeners that they should sound better. The truth is always the way to go: they don;t sound better, but that doesn't mean you shold buy the cheaper amp, unless you want to!

Hope this adds more perpsective to the debate.
-akhilesh

PS. TO directly answer your point about all solid state amps distorting sound the same way, the point is: if the original signal (WITHOUT an amplifier) and the signal through the amplifier differed only by say 0.3 db from 15,000 Hz on up, you couldn;t hear it. So dsolids state amps do NOT distort or alter the signal in any audible way.

There is this thought that solid state sounds dead, but I would say it;s the opposite: Tube amps sound LIVE. In other words: tube amps do stuff to recordings that make them sound more live. Solid state amps pretty much reproduce whatever shlock you feed thru them, and a lot of the PM out there IS schlock!
-akhilesh

Is it possible that the human ear can distinguish artifacts not readily apparent to a distortion meter? Why; if people say they like certain sounds and those people have not been exposed to this debate or do not know of the controversy surrounding whether we can genuininely tell if an amplifier sounds more like music than another amplifier does; must we negate their opinion as naive or useless?

What about the people who never seek out high end gear or study how to listen to it or know nothing about it; or how much it costs; does their opinion count?
These are the questions that plague me about this debate. We all know the usuall responses; they are impressed with the cost;
They are impressed with the looks;
They have a personal agenda, etc etc.
But what about the people who know nothing of the equipment but play music on instruments; would their opinion count?

I think it is too easy to dismiss the ones who listen to music but don't care about the equipment because they are not having this debate. But they should be the ones to do the tests with.

THe question of whether a signal is completely described by these aspects, or of there is a mysterious "X" aspect that will distinguish two signals that are identical in every way known to engineers is outside the domain of signal analysis, and could be termed philiosophical in nature. I suspect this "X" aspect is really the internal state of the listener, so, in a good modd a signal will sound one way to the subject, and if he/she were in a bad mood, the identical signal (identical from an engineering perspective) will be perceived quite differently by the same subject.
-akhilesh

John,
In my post above in this thread, this is addressed. I have reproduced teh relevant text below:
"The SECOND approach is: Buy imperfect components that somehow "mesh" together, often by cancelling out each other, and adding euphonic distortions, etc, and somehow make the whole sound musical. Often, they may actually make poorly recorded material sound more "natural" and also counter room issues.
I believe ALL tube amp owners follow this approach (whether they admit to it or realize it or not)! It's fun. and can result in suprprising good sound, not to mention a collection of fun TUBE amps. "

BTW, John, I have serious doubts that a stradivaius will measure the same as a cheap violin. It will differ along many aspects that are measurable (freq curve, distortion, spectral decay, etc).
thanks
-akhilesh

A couple of points did peak my interest though and I will comment.

1. Among classical musicians, some of the finest artists have some of the most awful stereos, and I don't use that word lightly. Thinking is that they KNOW what the music sounds like in concert. They are only listening to the performance, the notes. Some of these folks can have a thoroughly satisfying musical experience by simply reading a score. I guess it says something to listening to the music or listening to the equipment.

2. Just of historical note: Virtually all of the playable Strads, Guanerii, Amati, etc. have been destroyed twice. Once in the lat 1800's and then again in the early 1900's. All of these instruments were rebuilt to allow them to play louder and to accommodate metal strings at a higher pitch. They sound nothing like what the makers intended.

Bob