The one thing that really stands out to me is how dynamic the midrange is using my amp is on my upgraded Forte II's. I've never heard a SS amp do this. In my limited experience, of course.
I don't doubt that, subjectively. Recent anecdote: when I replaced my Mk IVs (and an 'updated' PAS look a like) with the AHB2/DAC3HGC (and external phono stage) I too experienced something like that, and frankly thought the Benchmark combo didn't sound as good as the Dyna.
But I know that it is easy to fool oneself, and the next day I fired up the Benchmark, and that combo sounded better, with 'tighter' mids and lows, and generally more 'strength' (if any of that makes any sense at all). How much is just imagination? When you go to the ball park, the dogs always taste better than those you water boil at home, on your stove.
Now, in a DBT could I tell the difference? Levels matched, and brands hidden? Possibly, with a 60 year old tube design v a SOA (in the distortion department) SS amp. Possibly, differences could be distinguished. At least it wouldn't surprise me. I'm not going to worry about it, and in any case, I am happy I have both.
I admit that for me, as a hobbyist, it doesn't really matter. For ASR, however, the idea (as I understand it) is to decide the best engineering given what is out there, and given what one has to work with. But there has to be some grounding. Some overriding perspective to it.
I've always thought that comparing tube to SS makes little sense. It did in 1960, but not today. We know (or should know) the results before we even start. I mean, when we take higher math we don't have to go back, on the first day of class, and prove the Distributive Property of multiplication and division. It's one of a foundation that we know and accept. Likewise, we 'know' that anything you can do with a tube, you can do better (electrically) with a SS circuit. It's just the way it is.
Before ASR there was Peter Aczel (in his second version of his
Audio Critic). Peter refused to review tube gear, or take it seriously, because he was looking for 'the best with the the less', as it were. His analogy: If I was looking for the fastest land animal I'd want to investigate the thoroughbred race horse, and not the donkey. I'd certainly consider the greyhound or the Afghan hound, but I wouldn't mess with a Pug. Maybe check out a cheetah or jaguar, but probably not your overfed lap cat. Of course that doesn't mean a donkey can't pull a cart as well as a racehorse, or that Snoopy or Garfield can't calm your nerves in a way a cheetah or high strung hound probably won't be capable of.