Hi-End Terminolgy Question for JV

JV:
 
I recall reading in another on-line forum (or maybe here) your description of the sound of the John Curl-designed A21 and JC-1 power amps as smooth-sounding and reasonably detailed, but also somewhat "dark" in overall character.   I believe you also made similar obervations in connection with your formal review of the A21 awhile back, and in connection with your experience listening to the JC-1s driving SoundLab M1s at various audio shows.  You use the term "dark" quite frequently in your review of solid-state electronics more generally, especially amplifiers.    
 
By "dark" do you mean a general lack of energy in the upper-midrange/lower treble region (with the attendant reduction in "air" and "openess") relative to better solid-state designs, and tube designs in particular, or does "dark" refer to some other type of coloration?
 
On a related note, John Curl seems to have designed the JC-2 preamp in such a way as to avoid what you perceive to be the traditional weaknesses of most solid-state designs, namely the same lack of air and openess described above. If Curl could succeed so spectacularly in delivering these sound qualities with the JC-2 at the $4K price point, why have solid state electronics designers working at, and even above that price point, not delivered similar levels of air and openess to the sound of their power amps? Is this an inherent limitation of solid state amp designs under say, $10K?   
 
I'd like to buy a JC-2 at some point, but am concerned that the only amps that might match its senes of "openess" and "air" will cost many multiples the JC-2's modest price.  (BTW, JC-2s are going for about $2400/used on Audiogon). 
 
Thanks,
 
Amandela77