I’ve heard the ProAc DT 8 powered by tube amps of similar output and I liked what I heard. I heard the Zu speakers powered by solid state amps. The Zu’s are extremely dynamic and exciting, but they have a hard edge to the attack of notes and can sound quite brittle. This is a speaker that I think is very polarizing; I know a number of listeners who thoroughly hate it (I kind of like it, but I also understand why it can be so off-putting). I haven’t heard the Triangle speaker you are considering, but, I’ve heard others and generally like the brand.
Good luck on your search.
Good luck on your search.