Is an autoformer (AVC) always superior to pots and resistors ?

That initial statement was intended to address the different volume attenuator options, as discussed in the OP.  My current rig includes a passive resistive unit into an active buffer.  The icOn 4PRO is a passive preamp based on Slagle autoformers.  It so far seems to sound better alone than it does run into the buffer.

I doubt the guide on grounding and shielding connectors in active equipment presented in the form of the AES Standard 48-xxxx (2019 Draft Revised), applies to the icOn 4PRO, since it is a passive unit. Fortunately, I cannot detect any noise issues when using the icOn.

My concerns are functionality and sound quality, and right now both options offer similar functionality and pretty good sound quality, which is up there with the many good preamps I have owned (including a tricked out MP-3). 

Mitch, I think using an additional set of interconnects, vs the icOn going direct into amps, might make this " test " invalid to the discussion at hand ( apples to apples / apples to oranges ), although, what ever sounds best to you. My best....

@mrdecibel 

The only "test" is for me to compare the icOn AVC preamp against my current Hattor/SMc buffer set-up, for the sole purpose of determining which of those two options sounds better to me.  If the icOn sounded better through the buffer then that would be ok too, but that doesn't seem to be the case - it sounds better as a stand-alone preamp.  I haven't yet decided which will remain in my main system.