Have heard the C.A.T. JL2 on numerous occasions and it never ceases to amaze me,for a tube amp its bass is unbeliveable and for its power rating it can drive almost any speaker effortlessly.As for the pre-amp a sig mk 3 is a big step above a mk 2 so I would start there.C.A.T gear is really addictive and built like a tank.Hope this helps.
Robert
Robert