With the RX-Z9, the NS-8HX would be perfect match.
As for Yamaha making poor speakers in the past, it was due to Yamaha withdrawing from the US market with their high end speakers. In the 70s when the berriyum NS-1000 were released, not only were they way ahead of their times, most major studios across the world used them including Danish Broadcasting Center and as you may know, Denmark makes a great speaker by the name of Dynaudio.
Go across major studios and what do you see, the white coned dimunitive speakers are the legendary NS-10M monitors, over 170,000 have been sold worldwide, mostly to musicians and studios.