I agree with you that SETs sound great. In fact i just listened to my quasi single driver home brewed setup with my set 45 amp today and really liked it. I still think that SETs sound different from other amps becuase of the 3 reasons in my post above. In fact I know this to be true... i don't just need to take it on faith. However, this does not mean that's bad: otherwise i would not own SETs! I LIKE how they alter the signal. But that they alter the signal can be easily proved.

In terms of what is fidelity: that is a matter of semantics,right? If you define it as something one BELIEVES is accurate, then that is one thng...if it is defined as something measured as accurate, then that is another thing. I think most people would define it as the measurable faitlhful reporoduction of an input signal at hte output...but hey....who cares? It's all semantics.

Also, many of us may be interested to know that anything a SET amp can do CAN be duplicated in an SS amp, in fact Bob Carver did produce his amps in the mid 1990's with 2 outputs: one with low impedance and one with significant impedance (to reduce the damping factor). Tailoring a frequncy curve is not a big deal either. Neither is introducing audible even order distortion. All of these can be introduced in an SS amp. Anything a tube amp can do in terms of amplifying a signal, an SS amp can do.

The good thing with an SS amp, if someone like Bob Carver were to do this again, would be to offer us CHOICES: like, a set of settings for a 300B type effect, another for a 45 type effect, and so on.
That would be really cool!
I await such an amp. Maybe some DIY type here can figure out the circuit for us!

The reason why such a thng is not done, in my opinion, is becuase most amps today are based on commercial chips, and no chip designer will design an amplifier that would conform to the specs of a tube...they'd be laughed out of the business. What we need is a dedicated discrete digital amplifier! But if we have to use those, may as well use tubes. Hence the current state.

PLease do not take this as a criticism of SETs: I LOVE them. 3 out of my 4 amps are SETs. But that they do the three things in my earlier post can be easily ascertained by talking to electrical engineers who are old enoughto have had tube training!
-akhilesh