Best amp ever made as far as I'm concerned.
I owed the Rev 2 and spent quite a bit of time on the Twin Jet.
The Ultra i had was the 6L6. It couldn't get exactly Rev 2 but i would say 90% there. Hard to compare as I had the Rev 2 YEARS ago but the Ultra is better.
Definitely more brutal, way more options, better cleans and just all around incredible.
You can get lost in it and may take months to figure out. Can do the Jose thing if you wish, crazy doom tones and Ultra brutal metal.
For me it has 2 shortcomings. First off it is the noiseist amp ever made and absolutely needs a gate. Absurd the amount of noise.
Secondly, I wish it got just a little tighter. Like Engl tight or whatever would be cool. I play fast and technical death metal at times and found myself wishing it responded a little faster and got a little tighter. It can definitely pull it off but I have to be honest, if it responded faster and got tighter if desired it would be the perfect amp.
Extensive research and testing yielded not possible as it has something to do with B+? Idk much about amps but it was discussed on SS.org
Anyway, those were my only quams and it's still the best I've ever played.
Had to sell it due to life issues but I will have another one day.
TlDR best amp ever made. I've heard some people say it sounds like a cardboard box and that the Rev 2 is better, couldn't disagree more.