It depends on what era we are talking about:
WTF and CoE both have spanky, mid rangy high gain tones. Legend has it WTF was Mesa Boogie Dual Rectos. CoE was Bogner Uberschalls with ubercab.
White album, no idea but I would guess still continuing the Uberschall trend.
Nightmare I think I read somewhere was using Marshall’s. Probably modern high gain heads (220X, Silver jubilee, etc)
everything after that is a mystery to me, or has a Hellwin on it.
Exact settings are probably a bit of a reach as so much goes into tone. Probably most importantly are which guitar you’re using and how you play it.
I will honestly always be an advocate for never trying to copy exact tones. trust me. I’ve searched for snippets and masters to get an analog of the CoE, spent hours referencing with a kemper and similar equipment to what they would have been using. But what you’re listening to is a polished final result that went through extensive production and tweaking with very expensive gear and very trained professionals, played by world class players.
that doesn’t mean give up! Try to make your own thing with what you’ve got. Make it as good as it can possibly sound to you, and always try to improve so it sounds like YOU. Obviously if you have trash gear search for upgrades, but going on thequest to sound exactly like syn is a fruitless one!
WTF was likely Dual Recs as you mentioned, since they were using them live around that time. It's also somewhat likely there were some Bogners on there, since Mudrock produced this and he loves some Bogners.
CoE was definitely Uberschalls, I think some Dual Recs, and also blended with a custom Bogner that Mudrock borrowed from Bogner and later had his own made.
Self Titled was Bogners and a Marshall, as seen in the "Making Of" documentary, along with the recent "A Little Piece of Heaven" Breakdown video. You can see the custom Bogner I mentioned before, an Uberschall (I think?), a Bogner Shiva, and some sort of Marshall, possibly a JVM (they were also released that year) or maybe a DSL.
Nightmare was Marshall was a blend of Marshall JCM800, Bogner Uberschall, Marshall JVM, and Diezel VH4 as stated by him here
https://www.guitarworld.com/features/avenged-sevenfold-afterlife.
HTTK was likely largely Hellwin, or possibly a Marshall JVM, and also possibly some blending of the previously mentioned amps from albums before. The Marshall/Hellwin theory not only makes sense with what he used live at the time, but also because of the more classic sound they were going for at the time. In
this studio clip, you can see a Diezel VH4 earlier on, as well as some Orange amp. Later in the video, you can see a Bogner Uberschall Twin Jet, and some other amp I can't make out that's on top of it.
The Stage has some of the aforementioned amps, and some new ones. In
this studio video, there's a Hellwin, JCM800, a Wizard amp, a Jet City 333 (which Zacky is known to use), a Mesa (possibly Mark V), a Bogner (not sure it's an Uberschall, could be a Goldfinger since Reinhold Bogner himself told me that they got some of those amps from him), and an EVH 5153 Stealth that's underneath the Hellwin (hard to see, but there was a clip in the video where I saw it clearer.