Horn speakers , high efficiency but not “shouty”

have a look at the Polish hORNS speakers, I've owned the Mummies for a few years and upgraded recently to the Symphony 13.

My experience, using the older Avantgarde Duo, which could sound great or terrible depending on set up, was that the associated equipment upstream could make or break the results. The synergy with the Lamm ML2 is a known relationship-- I'm not advocating amp or speaker, but together they bring more than the sum of their parts. As I changed out gear gradually to what is currently in use in my system, added subs and readjusted the integrated woofers to more closely align with the mid horn, changed cartridges to something that delivers more deep bass, the overall quality of the presentation has improved. It's not just the speaker. My puzzlement now, much as I love the character of the original Lamm SET, is to find a set of speakers that will eventually replace the Duo but can still work with the Lamm at a meager 18 watts/channel. 

I'm have been using Altec 604e since 2005.
I used Mordaunt Short, Dynaudio and Spendor 2/3 before.  
Horn and compression drivers are much more sensitive to equipment issues.
For example, I have 300B amplifier with 6f6 driver. When I started to use it Spendor sounded smooth but Altec sounded harsh with it. The reason was cheap 6f6 tubes. When I changed them to good Mulard 6f6g all harshness is gone.
Since that time I did a lot of tweaks in my electronics. And I can tell Altecs with compression drivers horns can sound smooth and refined. The quality of vocal reproduction is better then most speakers I listened on other systems included audio show.
And in addition you get a real, uncompressed dynamics, huge soundstage, live energy, realistic bass and other unachievable by low sensitive speakers.

03-12-2021 8:08pmI have owned Wilson and Sonus Faber and I will easily vote for a horn over either of these speakers.  I went on a year long search for Horn speakers and considered many including Charney, Avantgarde, hORN Univesum, Deja Vu, Klipsch, JBL, Aer, BD Design, PureAudioProject Trio's and Odeon to name a few.  Then I found this small boutique company called Viking Acoustic who does amps and speakers.  I ended up buying Viking Acoustic Grande Voix's and I am super happy.  They have a line of speakers in all price ranges.  

I agree with willgolf - the Viking Acoustic speakers (formerly dc10Audio in Santa Fe) are exceptional, with all of the benefits of horn speakers and none of the weaknesses.  They're very efficient, are easily driven with tube amps (SET amps and others).  Magical sound - among the best. 

I have the Berlin R MKII stand mount monitors and they sound superb - just as in these videos! 

http://www.youtube.com/results?search_query=viking+acoustics+berlin+r
   

Here are my videos of my Altec 604E

Heifetz - Sibelius Violin Concerto
https://youtu.be/LYXm9NL_RuY

Louis Armstrong ‎– Satchmo Plays King Oliver "St. James Infirmary"
https://youtu.be/l4iTxmxvJfU

Reiner - Chicago Symphony - Rimsky-Korsakov Scheherazade
https://youtu.be/trdFb6zO9OA