Proac using 'x' in their passive crossover this doesn't really generalise to 'typically' although I'd like to see the boards at the factory.

The devices measured by 'Ralph' and 'Shin' were 8 Ohm. We don't know whether the 16 Ohm variant is equivalent or not. At first glance putting more wire onto the coil must change things.

I don't know whether ATC make 'special' units for their own speakers, but I don't see any good reason why they shouldn't.

You said 'Certainly when crossed over at 500hz and properly EQ'ed the dome has none of the charaterisitcs detractors find off putting in the ATC monitors.' which clearly wasn't a complete statement.

I don't know the details of the ATC active or passive crossover so I wouldn't comment on it. It seems to me you don't know either but are happy to jump from effect to cause and then suggest a solution.

Have you ever had any dealings with race engine builders? They're a bit like speaker designers, the other guys compromises are always wrong....

Paul