I managed to get one and it pairs extremely well with HD650. Doesn’t leave me wanting more with the 650, which is the first time I can say that about an amp for them. A bit warm though, so not gonna be for everyone.

Magni is too harsh for the HD800 imo. Not the worst thing for them I guess, but HD800 sounds best with tube amps. Garage1217 Project Horizon 3 under $300 would pair nicely.