Okamoto, those tube amps seem to favor higher impedance if youre getting such a low amount of power at 32ohm. I would look into something that favors higher current, low impedance which would be better suited for planar magnetics. Maybe OTL tube amps? I will eventually get one too, not too expensive.
Any particular model in mind?
The only one i know is the Bottlehead Crack, but it seems it also favors higher impedance cans.