I am a Pass Labs lifetime customer, but I too was enticed by the active atc story. the amps are a-b not class a like pass so not as liquid sounding.
I had the 15" actiive three ways (5 years ago or so). it was impressive in many ways but the integration of the drivers just seemed off a bit. Maybe the newer ones are better. I bought mine used and sold them in 6 months for what I paid for them so it was a nice adventure. I would have to say that looking at the amps ( I took them apart) i wasn't impressed by the build quality. Just the clutter, soldering wires etc. struck me as a bit dated. I went back to Pass and passive speakers. Pass is known for really clean designs so maybe I am spoiiled. But the active thing makes a hell of a lot of sense. Even Nelson Pass made a big active speaker.......few bought it though...........