I used to own a couple of HH Scott components (amp and tuner) that I had my friend, George Wright (RIP), work on for me. One of the things he pointed out was that he felt some period NOS capacitors were superior in sound to his ears than any modern day equivalent. He had quite a stash of them in his shop. Alas, I do not recall specifics there, and that's just one person's opinion, of course. Capacitors certainly can make a difference in the sound of a component. I would definitely give the new caps 200-300 hours of playback time (running a signal through them) to break them in. I'd agree with some of the general comments thus far that imply that the magic you are hearing is a subjective response to the way the amp colors the sound and where it may add distortions. Different amps = different flavors and the magic part is entirely subjective. I don't know that I'd go as far as to say all amps with a certain tube type are likely to sound alike - in my experience this is far from the truth, though you can generalize about specific tube types. Just generally my impressions of the Cary and Conrad Johnson gear I've heard would have me point to them as warmer (read: "tubey" or whatever adjective you prefer to describe such traits). It's really a tough call to determine what your "tube magic" sounds like, compared to my own version of that, but having owned the Scott amp I'd think those two would be a good place to start.
