A lot of bashing of Black Metal tone on this forum. I can understand that some of you are put off by the sound of old Darkthrone and such (I personally love it since it's more about feeling than tone), but to say that "Black metal tone in general is really bad" basically means that you have no idea what Black Metal is at all.
I've been producing BM for almost 10 years, I've done all kinds of weird things when it comes to guitar sound, but I always stuggled to 1) find something that fits the music of the band of course and 2) find a balanced sound. And guess what! I use Engl Fireball. I use Peavey 5150. I use Rectifier. And I dial in the same kind of sound as you do probably. It's a matter of HOW you play it, mostly. But if you want to be narrow-minded, that's fine by me.
Anyway, to try to be on topic briefly. I don't know what they used, but maybe you can get in touch with the band directly and ask them what they used. It's usually no big deal. I've done this before with some bands and they're usually pretty helpful! Or you could also contact the studio of course (Shimmer Recordings in this case).