I'm nearing the end of a 30 day trial with the Operetta 5140 -- 5 channels rated at 70w/ch 8ohm, double for 4 ohm. Very interesting design choices and seeming attention to detail. solid and thoughtful engineering from what I gather and read (though I don't pretend to 'know the numbers'). You can google Jaton Operetta to read what little there is on the net right now. Anyway, this is a keeper for me and I believe destined to become something special. I took advantage of a 30 day trial with free shipping to (and even back if I decided not to keep it -- what a wonderful way to demo, and certainly putting their money where their mouth is!) and I believe the 5140 is still on sale from the normal $1600 down to $1200.
This amp won against 2 Emotiva LPA's bi-amped. Trumped them across the board, but most impressively (and surprisingly) in the bass dept. Huge bass, and a very nice sound overall. Jaton is trying to break into the market so reviews and news aren't abounding, but I do know that George is doing all he can to promote the products, going to trade shows, making generous offers, etc.
Just thought I'd start a post and see if there are any others who've experienced this amp line.