The whole issue of low impedance Apogee speakers and the H2O's ability is irrelevant. Since this is not the case for the A1's, discussing an amp that handles sub 1-ohm loads is a "don't care" issue in this thread.
Pure and simple, if you have invested in a $15k speaker like the A1, you need to put the same amount of attention to find an amp of the same calibre to hear what you paid for with the speaker. Again, pure and simple - the H20 does not cut it to convey the many awesome strengths of the SoundLab speakers. We can talk all we want about driveability, but again, this has nothing to do with musicality - the portrayal of space, silence between the notes, dynamic contrasts, ability to play material with a high level of low frequency extension and not have the mids and trebles crumble at the same time, etc., etc., etc.
The CAT amp is not euphonic at all, and the one JL-2 will not generate that much heat. You really should try to hear this to get an idea as to what your speakers are capable of. And try to get the H20 on loan so you can even more greatly appreciate the CAT's ability. Once you hear it, the H20's will be gone.
John