Mosfet mist?


Greetings,

I have read several articles on the sonics of mosfet amps to include Adcom,B&K,Counterpoint,Perreaux,etc. What exactly is mosfet mist and how would one know what to listen for. Are some amps more prone to this mist than others? I have a Perreaux 1150B doing woofer duty on a pair of Focal 706s spkrs(A modified Parasound 1000A on top)How would say the 1150B compare with a B&K in relation. Thanks.
south43
I have tried this, but it's hard to be precise with the +/- Variac sweep with the 3D glasses on as it is hard to see, plus I am mostly in the dark here. I thought I detected some smoke/mist coming from the Variac, but nothing from the speaker terminals. Also I have blown a couple fuses in my amp. Are you sure this is the way to do it?
My friend is currently running a B&K Pro 10 preamp, B&K 2020 amp I think, Marantz cd player.... powering MMG Maggies. I hear no such mist. Sounds detailed and clear to my ears. Seriously, I've heard much worse in systems costing 3 or 4 times as much.