The Carbon 7's have a relatively smooth impedance curve so they are fairly easy to drive. I've used low power tubes and high power SS, they both work very well. Never used Virtue amps before but if your room is small then it should be fine, otherwise a budget SS amp off Audiogon like a Parasound or Adcom would really make the Carbon 7's sing. But again, not picky about amplification.
As for replacing the Studio 20's, that's going be a night and day difference. There's another Carbon 7 owner who replaced his Paradigm Studio 100 towers, he's extremely satisfied.
As for replacing the Studio 20's, that's going be a night and day difference. There's another Carbon 7 owner who replaced his Paradigm Studio 100 towers, he's extremely satisfied.