There is a relevant review to this group , August 2007, by Mark Michelson, Soundstage, where he compares the Atma shpere MA-2 to the CAT JL-2 Signature and an Audio Research, which is a must read to all the participants of this discussion.
He praises the mid range of the MA-2, but finds the CAT as the most dynamic, weighty, powerful and probably the most balanced amp of the three and one of the best available at any price, certainly at half the price.
I don't own either amp, have considered both and others, as I am looking for a new tube amp, with dynamics and finesse for my system.
Louis