Speaker recommendation for SET tube amp MASTERSOUND

For over a year I've been contemplating a SET tube amplifier for my Sonus Faber Elipsa SE.
I know SET is a poor match for a relatively inefficient and difficult to drive speakers, nonetheless I was completely entranced by this amp. 
 I finally got a Mastersound Compact 845. The sound is truly magical, even at low levels, and considerably different from my Mcintosh mc452/ c2600 combo. 
I'm reluctant to test the limits of this amp due to the fear of over driving the amp and damaging both the amp and speakers. I haven't moved the volume dial past 11 o'clock. I listen to classical music, mostly piano and symphony. So far just solo piano nothing dynamic. I've been listening to this amp religiously 2-3hr a day since I got it. I wasn't compelled to turn on my MAC even once since I got MS. 

I know I need efficient and easy to drive speakers to really enjoy this amp. I prefer speakers that look modern and attractive, ie sonus faber style. Ill set it up in my bedroom which is 18'x14ft with vaulted ceilings ~12'. Alternatively my office with 16'x11' with 8' ceilings.  Ill be using blue sound to stream Tidal. What would match well with this amp? Regardless of price, what would be best for my music choice? I know this is a backwards way of setting up a system, but I absolutely wanted Mastersound and nothing else. I would like to stress one more time, aesthetics are very important due to WAF. These could be monitors or floor standing. Here are the specs for Mastersound Compact 845: 

Power: 2 x 30 Watt
Tubes: 2 x 845 - 2 x ECC802 - 2 x 6SN7
Inputs XLR: 1 Line + 1 Direct
Inputs RCA: 3 Line + 1 Direct
Bandwidth: 8hz / 40khz 0 db
Load impedance: 4 – 8 Ohm
Find a pair of Snell E's for cheap! This is the original design that Audio Note UK copied and called the EIII (for a mere $4.5K). I have a pair with replacement SEAS 8-inch drivers. A great-sounding floor-stander, easy-to-drive with tube amps!
Not sure of your budget but the Charney Audio Companion with your choice of driver will work perfectly with your amp and room. Charney will custom make your speaker to wood type and colors to fit your decor. The Companion is a work of art that delivers music in spades. If your in the NJ,NY,CT,PA region contact Charney in Somerset NJ for a listen. Or do a search there are a number of happy owners on the web.
I used 15” tannoy with 845 with good result. Also Altec 604.  More in keeping to your modern look i used reference 3A
Since you stressed that aesthetics are very important and price does not seem to be a factor, the Voxativ Zeth or Zeth-B may work for you
What about Zu audio cube? Or do I need a speaker of higher caliber to better match the quality of my amp? 
My wife likes the look of my SONIST CONCERTO 4's and they are very easy to drive, in fact I'm using a 5 WATT amp with great success! And their in a room that is a little larger than yours.

Good Luck, TISH
I'll second analogluvr about Ref 3A.  I have a pair of Ref 3A de Capos i have used with 30wpc Primaluna PL2 and currently a 4 watt Decware.  Even with just 4 watts it still gets loud enough.  It is detailed and but rich. decent bass for a standmount
Maybe take a look at Daedalus Audio, Have Argos V2s driven with a Line Magnetic 518IA 845 22 wpc set integrated (also drive them with 2 other amps I swap in and out)  Daedalus speakers are beautifully handcrafted wood and finish, 6ohm flat , high sensitivity, easy to drive , musical
Zu works well with this amp
Wavetouch Antero speaker should be great match with your 30watts amp. Below video is with 15watts SS amp in room (size 13.5’ X 21’ ) with few acoustic foams.
Alex / Wavetouch audio

what does the impedence curve look like for those? Not particularly sensitive at 87db and 6ohm. 
the only spec given is 3 ohm min.
the secret is in the quality of the transformers.
If you are interested in Zu, call the company and talk to one of the team. They are a valuable source of advice.
You can try a more convencional speaker like the Paradigm Persona 5F.

Absolutly great speaker to be drive by a tube amp.

I have a Persona 9H with Triode M845...50w classe A SET amp....a fantastic combination.
Have you reached out to @audiothesis ?  Skip represents MastersounD in the U.S.
What about Diapason adamantes ? These two brands have been seen in many shows. 
@ei001h Nelson Pass has used Tannoy's while developing his First Watt amplifiers... almost all of which are under 30 W per channel.  I'm not familiar with all the models, but at least some should be a good match.