[Baxide]

  You can make a SS amp distort like a Tube amp. The 2 are different in their distortion characteristics and noise floor. Given a certain volume level (tolerance), it is near impossible to distinguish in a double blind test. You can immediately tell when they reach their boundary conditions since Noise floor and distortion levels of a TUBE amp will reveal itself. 

I have had the pleasure of playing with loads of amps, and quite a few of them were valve amps. The thing about the valve amps is that you can drive them into excessive distortion levels, but still experience a pleasant sound coming out of them. The Marshall amps are a good example of those pleasant distortions. Do the same with other kind of amps and the results are quite the opposite.

 

[sinesweep]

 
I have had the pleasure of playing with loads of amps, and quite a few of them were valve amps. The thing about the valve amps is that you can drive them into excessive distortion levels, but still experience a pleasant sound coming out of them. The Marshall amps are a good example of those pleasant distortions. Do the same with other kind of amps and the results are quite the opposite.

 

I wouldn't say pleasant, but different. If you take your Marshall amp and measure the output with a B&K SPL meter within the amps comfort zone say 85db from a sitting position from the speakers. Then then have a friend swap the amp with an SS amp and measure the output and listen. Then cover the equipment and have your friend switch speaker leads without telling you. Repeat 10 times given that you have no idea which amp is used. IF you can accurately detect which one is your Marshall amp more than 50% of the time, you have better ears than majority of sound engineers and mastering engineers. I know Mastering engineers that can detect sound level peaks and valleys from listening to pink-noise.

The key here is 
1) only the amp is swapped and they have to be set to produce the same output level of 85db measured at the listening position
2) given that output level it is within it's nominal operating range.

 

[Baxide]

IF you can accurately detect which one is your Marshall amp more than 50% of the time, you have better ears than majority of sound engineers and mastering engineers. I know Mastering engineers that can detect sound level peaks and valleys from listening to pink-noise.  

I (and many repair engineers in the audio field) probably have far better hearing for such things compared to sound and mastering engineers. In the repair business you need to have exceptional hearing. Nobody likes to return their equipment to the repair shop because of any issues with it not having been fixed properly. Especially when dealing with expensive gear and customers who are not short of a few bobs. Judging by the loudness war, and the multitude of diabolical audio mixes out there, I wouldn't consider sound and mastering engineers to be a good source of reference as far as sound quality is concerned.

 

[sinesweep]

Judging by the loudness war, and the multitude of diabolical audio mixes out there, I wouldn't consider sound and mastering engineers to be a good source of reference as far as sound quality is concerned.

 
 
yeah I know a mastering engineer that was at Sheffield Labs (when they existed). Not really a bad SQ label. Trust me, this engineer knows sound.

 

[Baxide]

   
 
yeah I know a mastering engineer that was at Sheffield Labs (when they existed). Not really a bad SQ label. Trust me, this engineer knows sound.

No doubt there are a couple of good ones out there. But most of the ones I know are suffering from hearing problems. Let's just say that I lived up the road from the famous Abbey Road recording studio and BBC Broadcasting House in those intense repair days, and regularly fraternised with the engineers for social and business purposes.