Both the Harbeths and either Zu model are excellent speakers. You have more than enough power to drive any of the three speakers well, so you're not practically limited. I've heard the Harbeths, know the importer and own Zu, as a matter of background.
Harbeths are the kind of speaker I spent decades owning; tonally neutral, smooth, conservative in their presentation. All of this is to the good and by any measure the Harbeth 40.1 is a musically sincere speaker. Zu Definitions (or Presence, in lesser doses) deliver the tonal neutrality needed for credibility to a "neutral junkie" but deliver speed and tone density the Harbeth can't match. Similarly, the Zu speakers will be dynamically effervescent compared to the Harbeth's more reserved nature, and Definitions in particular will scale up to the sonic space of your large room.
Some people might hear the Harbeth as the slightly more frequency-accurate speaker, but this comes at penalty of crossover characteristics. Where Zu leaps ahead is in dynamic fidelity and the ability to recreate a better representation of the transient aliveness of real instruments. The powered sub-bass arrays in Def 2 and Presence are a bonus underpinning the music with a convincing foundation.
While Zu Defs and Presence have 101db/w/m efficiency ratings, unlike most full range driver speakers in that efficiency league, power handling is robust. You can use Definition with dreadnought amps without fear.
Phil
Harbeths are the kind of speaker I spent decades owning; tonally neutral, smooth, conservative in their presentation. All of this is to the good and by any measure the Harbeth 40.1 is a musically sincere speaker. Zu Definitions (or Presence, in lesser doses) deliver the tonal neutrality needed for credibility to a "neutral junkie" but deliver speed and tone density the Harbeth can't match. Similarly, the Zu speakers will be dynamically effervescent compared to the Harbeth's more reserved nature, and Definitions in particular will scale up to the sonic space of your large room.
Some people might hear the Harbeth as the slightly more frequency-accurate speaker, but this comes at penalty of crossover characteristics. Where Zu leaps ahead is in dynamic fidelity and the ability to recreate a better representation of the transient aliveness of real instruments. The powered sub-bass arrays in Def 2 and Presence are a bonus underpinning the music with a convincing foundation.
While Zu Defs and Presence have 101db/w/m efficiency ratings, unlike most full range driver speakers in that efficiency league, power handling is robust. You can use Definition with dreadnought amps without fear.
Phil