ATC or Audio Note (2-way)

ATC's are not midrange centric, they are not "smiley curve" sounding as so many speakers are.  Smiley curves sell MUCH better than flat speakers so they are vastly more popular.  Manufacturers know this as most are not in the business to build the best speaker, but to sell the best selling speaker.  If you like music, bass boosted smiley curve actually reduces resolution by elevating bass unrealistically compared to "heart" of the music: voice, piano, violin, guitar.  The midrange now sounds reduced, pushed in back, not like the band or orchestra or instrument really sounds.   This is why many in the high end "accurate" camp use piano for demo.  Its easy to hear changes to EQ on piano.     

Makes my head hurt that you would consider modifying a $13,000+ two-way speaker like the Super K’s having never heard them. 

+1 @ghasley

atc and audio note are the among the last speakers i would ever consider ’modding’

but hey its a hobby so peeps gonna do what they wanna do to be happy...  who are we to judge 

Thought both were very mid-centric?

it‘s what’s called a flat frequency response

so low level listening was their weak point, imo

you‘re using the wrong amp

Maybe, but my opinion was based on side by side comparisons of the ATCs and Audio Notes using two different integrated amps

Musical Fidelity A5

Luxman L-509x

The ATCs were great speakers - make no mistake; just compared to the Audio Notes they did not sound "as good" at low levels.