Short List of speaker Upgrade

Well you certainly have some good choices.  I’m unfamiliar with Triangle, but they have a good rep and I believe are usually relatively easy to drive.  I’ve heard other models from ProAc and Totem and was very impressed by both.  The Totems throw off an impressive 3D soundstage and disappear very well, and the ProAcs do likewise but have a naturalness about them that is very rare and what makes them one of my favorite speakers on the market.  These were different models so take that for what it’s worth — although I do believe both brands do have a house sound — but maybe something to listen for when you audition them.  Your ears will tell you which one is right, and best of luck. 

Ignoring the not insignificant influence of your bespoke room acoustic warts, your new speaker selection is largely dependent on what your upstream electronics are, and how they interact with the speakers. Both the electronics and the speakers )independently AND together …) all have their own bespoke sonic signatures.

System synergy matters, big time,I’ve personally owned TOTEM and TRIANGLE in prior systems and they are VERY different in their bespoke sonic signatures .

if you are simultaneously blessed and married to your local dealer, then your speaker choice selection distillations process should be relatively EZ , with a bricks and mortar hands-on personal audition series…. Just fuggeddaboud the blind and heavily biased 3rd party suggestion posts herein as a paralysis by analysis exercise, and embrace a dealer store visit and trust your own ears.

I currently have as follows:

1. Bryston 4B3 Cubed power amp
2. Bryston BP-19 preamp
3. Lumin U2 mini streamer
4. Chord Qutest Dac (seeking to replace with Weiss 204 Dac)
5. SVS SB 4000 pair of subs

Completely agree that if you are going to spend this kind of cash on a pair of speakers your dealer should be perfectly willing to let you try each model in your personal space, using your own equipment, and likely test each one for several days so you can make an informed decision. All of these speakers will be outstanding pieces of engineering, but in their own way, so you will need to test them all and see what you like best. That's it, nothing more. For that kind of money, it's all up to you to decide what you like, and not be influenced by opinions on a message board. Just my 2 cents. Good luck!

Sonus Faber Olympica Nova III. 

https://www.sonusfaber.com/en/products/olympica-nova-iii