Any of the amps that you recommend run 20 to 30 db of feedback!Bubble still up, your having illusions, or didn’t do your homework.
Two of the amps are "local" and not sound destroying "global" feedback, and are designed to be low output impedance with resorting to global feedback, and have huge reputation for stunning bass and speaker control especially hard to drive ones like these B&W 802d3’s.
I repeat 73max OP, don’t get autoformers for your 802d3’s, unless you have an amp already that’s not right for them and want to use them as an interim band-aid fix, till you get the right amp to do the job, then autoformers are not cheap around $700, better to just put it towards getting the right amp!
Cheers George