I found the Peavey Jsx to be inbetween a Mesa Boogie Dual rect and a Peavey 5150 but not as good as either, closer to the Mesa.
Its a good amp but when i tried it it wasnt close to as good as the mesa or the 5150.. im sure it would sound in place and really good on record i just think that theres nothing wow about the amp, Peavey sell the 6505 and Valveking for cheaper and i feel they are both vastly better sounding amps.
It was kinda fat but muddy sounding, it had a shite load of gain, i find it hard to beleive that satriani would willingly use this amp with his name on it.
Just my 2p as it were.