I now use the SL Kraft 250 and the SL tubed pre. I previously owned a CAT Ult MK2. I have also heard the SL SS pre with the Kraft. Bombaywalla and Jay are both right.
The SS SL with a 1 ohm output produces deeper tighter bass than the tubed SL or the CAT. The tubed SL does other things somewhat better than the SS SL. It is a matter of taste but I would choose either over the CAT. You may end up going back to the SS crossover to drive the amp correctly and may want the things tubes bring from the preamp.
Bart
The SS SL with a 1 ohm output produces deeper tighter bass than the tubed SL or the CAT. The tubed SL does other things somewhat better than the SS SL. It is a matter of taste but I would choose either over the CAT. You may end up going back to the SS crossover to drive the amp correctly and may want the things tubes bring from the preamp.
Bart