You may think your GAS is over, but you should get on the list to have the Sisma sent to just to try it out and compare it to what you already have.
It might not change your mind, or it might, you'll never know until you do so. There is no obligation to buy a Sisma, but you will at the least be more informed on what it is capable of.
I second that.
@AlexMG You cannot perceive the special "heft" of Sisma (or any other amp) with a Youtube demo, even with good headphones. It's something you have to experience loud and in context.
Now of course, if ending you GAS make you life more confortable it's ok for me, I don't want to be responsible for unwanted GAS
. As @Jeff Scott says, nobody needs to buy Sisma, in fact a lot of people including bassists are perfectly happy without knowing about it.