The Cat SL1 Ultimate Mk II preamp is a interesting piece of equipment. Some folks prefer it and some do not. I put myself in in later category. I recently just sold my Cat Ultimate but I know there are others which really like it. I have owned several SL1 Cat ultimates over the years starting in 1999 with the original Ultimate Mk I and more recently earlier this year I repurchased the Mk II to evaluate. My opinion of this preamp has changed with the passage of time.
The SL1 Ultimate does have some strengths. It is very clear and clean sounding. It has good detail and imaging and excellent bottom end extension on the bass region, perhaps the best extension at the bottom of any tube preamp I have heard and it is very quite especially with the MK II version. It also has a certain "see through" quality that can be very appealing at first. These traits of the preamp are what first attracted me with the first Cat Ultimate I owned for several years in the beginning. Now for the bad news. I was using my SL1 Ultimate as a line stage connected to the JL2 Mk II amp using the Manley steelhead phono stage. The Cat preamp lacks the substance, size, body and especially tone I have experienced with other preamps. The dynamics are mediocre and it lacks slam impact even thought it is very clear. When I was listening to this setup and closed my eyes listening to familiar source material I was doing less toe tapping. I was not as emotionally involved with the music as I was before. I was thinking to my self "where is the beef", or another way of putting it is "where is the flesh on the bones". The lack of body, flesh and tonal balance left me feeling this preamp was "soulless". There is a certain "sameness" from record to record with the Cat Ultimate. The texture and great tone I previously was hearing on my modified MFA Luminescence preamp were missing with the Cat. While no preamp is perfect and they all have certain shortcomings it was the lack of emotion involvement and tone I noticed the most with the Ultimate Mk II. I guess some people will like the Cat preamp for its strengths but for me to many things were missing.
I do believe Ken Stevens has hit a home run with the JL2 amp. I have owned one now for 3 1/2 years and I love it. I have no desire to change or sell my JL2 amp as the flaws I listed above are not apparent with his outstanding amplifier. The sense of authority, power and "see through" like clarity of the amp have me hooked on this product. A true reference piece and his Statement product. Hopefully Ken's new 15k statement preamp will resolve some of the issues I listed above.