tube amps sounding like solid state and vv

Unsound, the funny thing about that is that transistors sound better on 16 ohms too. I agree with you of course :)

Give a listen to the Music Reference RM9 or RM10 run passive through a Noble or equally good POT. You'll hear all the benefits of tubes without a tube sound.

i think a more interesting questions is the following:

why do designers persist in providing more and more resolution until it hiyrts ?

why should one suffer listening to certain recordings?

too much resolution does not sound real.

i believe that the result of designers' attempt to peel back so-called layers of veiling and noise to reveal all of the musical and non musical details of a recording creates the phenomenon that you are alluding to, namely, the convergence in presentation of tube and solid state amps and preamps. i don't think there is a deliberate attempt to create this convergence. i think it is a result of increasing resolution.

there is an optimum level of resolution for human beings. too much or too little is less preferable than the "just right" level. unfortunately manufacturers and hobbyists alike do not know what the optimum level is.

there have been many experiments in the psychology journals which deal with the subject of stimul;us complexity and intensity. it is obvious that when the level of clarity increases there would be a change in stimulus complexity and intensity. maximum intensity and complexity are experienced as unpleasant.

I think some designers try to get distortion and frequency response to the best that they can, at the expense of other probably more important parameters. Tubes often take a more reasonable stance- 1% THD seems high for a transistor amp but is common for a tube amp, which uses less feedback (and consequently might sound smoother). You get more a little more distortion but less of the types the ear objects to.

The bottom line is you still have to trust your ears. The benchmarks for testing won't tell you if the amp is really going to work.

Taijitu (yin + yang)?

Perhaps, like many dichotomies, neither tube nor SS can truly thrive alone?