Try replacing the tubes with EL34's/E34L's, my 6260 sounded way better when I put the JJ E34L tube set in, and replaced the v1 preamp tube with a Tung Sol.
Something happened with the quotes above in case anyone's confused. But on these tubes, I have EL34s as well in my Peavey, and I'm wondering if you found this out because a tube failed or you just experimented with different tubes? I have read a lot of recommendations for the JJs.
I only now a couple of those bands since im not really into grind, powerviolence, etc. But that's really cool, do you know any portuguese bands? Devil in me or For the glory, maybe? (not the best ones by far but definitely the most well know internationally) I think DIM toured with an australian band called Deez Nuts.
I haven't really heard any bands from Portugal except Simbiose (great band, very much the style of music I'm into, are there other crust bands in Portugal?). I haven't heard of any of the bands you have mentioned except for Deez Nuts, which I only heard about because they are included on the flyer for some show here. To be honest my punk knowledge and taste is almost completely '80s bands, and pretty much hardcore genres like UK82 (e.g., The Exploited), Swedish (e.g., Anti-Cimex), Japanese (e.g., Warhead), crust (e.g., Doom), crossover (e.g., R.D.P.), crustgrind (e.g., E.N.T.), and grindcore (e.g., Unseen Terror). In other words that fringe of punk closest to metal. I've always been in that area of overlap between punk and metal, although I never got into NYC hardcore or the more recent metalcore and deathcore scenes (not a big fan of breakdowns, although I liked the way Dying Fetus used them that is the exception). actually pretty much every genre that appeared in the '90s or later (including in metal, e.g. nu-metal, but also a lot of '90s death metal etc) I don't seem to like. I guess I'm an old fuddy-duddy at 46 now. Kind of sad! I think some of the basic guitar sounds though are similar, its more the vocal styles and songwriting that has changed. Actually powerviolence is the one new genre I've gotten into, but it has its roots in the '80s bands I mentioned above