I hate to be the boring techno person here, but Bob Carver was right. all electronic circuits have what is called a transfer function that determine what the circuit will do over frequency with specific voltage/current variations. Unless the amps in questions employ exactly the same circuitry, there is no way on this planet that they will operate or sound the same. If you look at the results of the circuit's transfer function you will see exactly what I am talking about. Bob Carver did something very cool and tricky years ago. He got a really high end tube amp (don't remember the manufacturer). reversed engineered it and actually determined the amps transfer function (this is literally an equation showing the voltage in/out characteristics showing resistance, capacitance, inductance impedances for the circuit) then he managed to actually design an amp with the same (or close to it) transfer circuit) to show that 1) he could do it and 2) he could do it to sound just as good or better than the other amp for less cost) and guess what? he did it. really good amp. My point is that each and every electronic circuit when completed has a vo/vin transfer function. So if you computerize the transfer function and run signals in over frequency, you will see the amps characteristics are totally different over frequency and phase. They couldn't possibly be the same. not a chance. Also, I disagree that measurements have limited use. If you don't use measurements, there is no way on this planet you could actually design any electronic equipment. You design amps based on detailed specifications, as I have mentioned several times previously, such as phase, frequency response, gain, input/output impedance, load handing (what loads are it supposed to handle over the power band width and frequency), etc. once designed and built, guess what? you have to put it on a test bench and ....... measure the responses to see if the amp performs based on your actual design specifications. Any yes, we can measure for sound of particular amps. This is definitely where transfer function responses come in. but, this is not cost effective and unless it is a military device, no way on Earth will this type of design be done for amps. But make it worth someone's while and specifications and measurements will be developed (already are) to tell you how it will sound. Right now it is simply not worth it to spend the time and extreme money to do this. Because audiophile and music reproduction is not large enough for scientist to invest that amount of time and expense to do this. But, let me back up here, there are some audio manufactures that know what particular circuitry does sound like, Nelson Pass, and many others, and what they do is incorporate that particular circuitry in their amps all the time. The only time they change is when they develop new circuitry and amps and listen for some time and like the sound over the previous circuitry. this is physical measurements using human ears, not paper and pen or computer measurements. But don't think for a moment it can't be done. This is a physical universe, of course it can be measured. We determine many things and science by reverse engineering. I thought Bob Carver's approach for that particular tube amp was great.
enjoy
