How to read speaker sensitivity rating?

The Kappa 9's, when used with their "extended/normal" switch in the "extended" position (which iirc seemed to be the most commonly preferred setting), are conceivably the most difficult speaker load ever devised by mankind, at least among home speakers.

In that mode they go down below 0.8 ohms at multiple bass frequencies, where lots of energy is typically required. I know of no other speaker that comes close to doing that, although I believe the Kappa 8's are not too far behind. The "normal" mode is not quite as severe, but still very challenging.

I don't know what their phase angle behavior is in the bass region, but it wouldn't surprise me if it was significantly capacitive, adding to the severity of the load.

I can't imagine that a Zu speaker would be anything like that.

Regards,
-- Al

The Zu's would be a much easier load for your amp.
And the Dominance is a dream speaker. I envy you.
You will also love the crossover-less design of the main drivers. They should be a move in the right direction for you.
John

Viridian also noted that phase angle will make a difference and maybe more than impedance magnatude. Of course, the amp killer speakers, no matter the sensitivity, have low impedance and adverse electrical phase angle in the upper bass, where much of the energy is. They are the gas guzzlers of the audio world and will suck current out of an amp like there's no tomorrow.

Will someone please explain "phase angle"?

FWIW, when a speaker's specs include both its sensitivity and its power handling capability, it allows the user with a similarly capable amp to estimate how loud the speaker will play safely and continuously. For example, ratings of 87dB and 150 Watts translate to a maximum volume of just over 108 dB, earth shaking but not shattering.