ok so, been looking back thru your posting history to try and get an idea of what kind of music you're actually trying to play, look s like you're into your metal.
Think carefully about buying a jet city. They are stonking amps yes, they kick the arse of most things in their price range yes, but am not sure the lineage is right for you.
As we all know JCA are, by and large, soldano designed with a few of the other independent manufacturers (THD) contributing some models. Soldano are one of the archetypal high gain amps, yes, and JCA do the best approximation of their sound on the market, in fact they get quite close, they just miss out some of the subtleties of the sound, but we're talking a mass produced amp at a fraction of the cost so no complaints.
Here's the thing, Soldano's can do metal very well, in fact they can destroy most other amps out there, but what they don't do, or at least are not voiced for, is scooped out metal of the kind that seems to be the fashion at the moment. what most metallers forget is the scooped sound they hear on records a) isn't as scooped as they think it is, and b) is the result of much production tweaking and, these days, more than a few plugins.. so a lot of people that buy soldanos or there derivatives are disappointed because it's not the sound in their heads. but thats because they're not listening to them right in a band context,and when they get them to the rehearsal room, they're scooping them and taking all the mids out, which is where a guitar lives.
they have a lot of preamp gain, but not the stupid amounts that end up as an over compressed mush that brands like krank are capable of. they are a very mid crunch voiced amp and as a result are very unforgiving. if you make mistakes, if your playing is sloppy, it won't get hidden behind a bunch of compression and harmonics. not to say it's not rich sounding or doesn't sustain, it does both in spades., but it's also very open and articulate and very touch responsive. you hear playing dynamics, you hear string separation, you hear all the notes in a chord, and also the notes in the run you just fluffed. Having mine, made me a better player, but i promise you i sounded like sh*t for the longest time.
It also doesn't have a huge booming low end, it has a tight percussive one.
If you need a quick fix, modern voiced, uber pre amp gain machine. this is not the amp for you. If you want a timeless voiced, agressive, responsive open, articulate, high gain bugger that makes you work hard to get the best out of it, the best being far better than anything else out there in the production world, then buy a soldano or it's baby brother here.
Look at the soldano website and see who's used them. always suprises me, given the reputation soldano has, the amount of guys who use them and aren't known for high gain craziness. says a lot i think