The complaints often leveled against “passives” relate to problems with dynamics and drive, as others have mentioned, but those complaints pertain to resistor-based passives, not magnetics.I have resistive, opto-coupler, photo cell, transformer, autoformer, and potentiometer passives. While I admit paying attention to impedance matching is important to maintain dynamics and drive, you can have those issues with any of the passive topologies, singling out resistive passives as a problem child is just plain silly. FWIW I also have Atmasphere MP-3 and Beveridge RM-1/RM-2 active preamps. My passives give up very little to nothing against them.
52tiger - I was curious about your question and if it is sufficient volume level to load the room then just turn it up. I operate my passives anywhere from 1 to 3 o'clock on the control. Slage's autoformers are well made. I have a set and they measured very well. Enjoy your Emia.