Jim H makes very good gear for very reasonable prices. I'm using one of his Trumpet designs that replaced a more expensive unit. As far as tube rolling, I'd say trust the tubes that are in it, for now. Those RCA clear tops are often considered pretty good, and JJ's have their strong points. Swap those out for a while. Later, if you decide you are looking for more _____ (warmth, detail, soundstage, etc) you can read up and look for bargain pairs on Ebay. My experience is that no tube does it all... they have strengths and weaknesses.