I was hoping Brian would chime in here but I'll go ahead and give my experiences with these two product lines.
First off the preamps: I have not heard the MP1 but have wanted to for many years. The MP3 was one of the most disappointing auditions I ever had with preamps. I heard it at the ARC/Atmasphere dealer and it only sounded ok. So I borrowed it for the weekend, tried it at home and at the BAT dealer and in each case, the frequency extremes were rolled off, with no air or spaciousness at all. It was no match for the ARC LS5 or BAT 31SE as a line stage. I did not even bother with the phono capabilities.
The CAT SL series has impressed me time and time again. It is more neutral than my favorite preamps of the last 20 years. I tended to like a more warm presentation which is why I went with the ARC SP-10 and LS5/PH2, later the BAT 31SE and Aesthetix Io, but I find myself more and more drawn to the neutrality of such products like the CAT SL1. There's an openness of this product that is quite impressive.
The amps comparison is quite different. For the few hours I was able to hear the MA1 vs. JL2, there were big differences. Unfortunately the MA1s were new and clearly not "broken in" but they had a lush smooth richness that was so very very nice. To say I was impressed by the musicality of these amps would be an understatement. And they had just a little bit of that lower midrange warmth that added body and dimensionality to the music.
I would have to disagree with Rushton on the issue of the Atmaspheres and added no warmth. When you hear it aside the CAT, the CAT is clearly more tonally flat. But keep in mind, I tend to like a little bit of this warmth quality as it can be addicting and involving and this was what drew me to the MA1s. They were a great match with the Soundlabs.
Rushton writes that the Atmaspheres have a quickness. I would agree with this until I heard the CAT play the same music seconds later on the same system. There is an attack on each note and gnat's hair resolution with the CAT that allows for detail to come through. This was so evident with intricate acoustic guitar playing. I could much greater appreciate the talents of the musician and the sheer speed of the fingerwork through the guitar strings with the CAT. This was NOT subtle. I would label this as a quickness quality.
For me, the CAT excelled in areas of dynamics and resolution and had a more neutral tonality. When you hear dynamic contrasts like this amp can do, you pause and sit at attention.
There is no clear winner here as both of these amps are exceptional products. What I wanted was an amp that had qualities of each of these products .... I liked them both that much. It comes down to personal preference AND ultimately the match with the speakers you own. The CATs are made to drive virtually anything out there whereas the Atmaspheres need to be more carefully matched.
You really need to hear these for yourself.
John
