How far have ss amps really come in the last twenty years?


I have owned and enjoyed my Jeff Rowland model 8 ( recently modded and upgraded by Jeff to the last version) for many years. I recently had the opportunity of comparing it ( after mods) to a few of the current ss models from Gamut, D'Agostino, YBA, Parasound, Sim audio, CH precision, Constellation,PS audio,Pass Labs  and Musical Fidelity. The results were very interesting, because to my ears and in the systems that we did the comparison, the Rowland held its own against all but the most expensive D'Ag and CH amps. Even those were only very slightly outclassing the Rowland in the areas of top end resolution...and a tad in the bottom end resolution. Now the thing is that the last revision to the Rowland 8 was designed by Jeff over ten years ago! 
So, my question for those more technically inclined than myself is...how far has the design of ss amps come in the last ten...or even twenty years? 
128x128daveyf
Doesn't seem like a silly question to me. Differing pace of innovation, both in product, and in particular aspects of products, are everywhere.  Have we changed how we dry clean much?  Air conditioners and combustion engines and vehicle suspensions work basically the same way, but innovation in efficiency has improved dramatically.  I don't think progress travels in a linear fashion.
So, the question that keeps coming up in my demented mind is, if the goal of high end audio is to reproduce the sound of live performances, why isn’t the high end defined by the likes of Crown, JBL, ElectroVoice and other pro audio items of reproduction? After all, unless you are sitting in the first 10 rows of a concert venue, what you are hearing is coming from the pro audio world. I can buy a lot of Crown amplification (substitute any pro audio product here) for the cost of A Gryphon or Dartzeel amp. Just wondering.
I am using an old Amber 70 in my second system that with the revealing Thiel 2 2's is more musical than any of my more modern power amps.  No question a thorough parts upgrade would improve transparency.  But not overall ability to reproduce music that sounds like music.
@wspohn

You make a good point.  Most every time you change a component and often when you change a wire, you end up hearing something different...but that doesn't mean that the change you hear will be appealing to you!