High end speakers at low volume

After having got accustomed to my new Vitus RI-101 mk II, I came to the conclusion that I need to improve my system's performance at low volume to enjoy music more.

Current sources: LinnLP12, Holo Spring 3 KTE, Nucleus. 
Speakers: Avalon Idea. 
Shunyata Delta NR V2 and Hemingway Indigo PC, Tara Labs Forté, TQ 2 Black diamond IC.

I am looking at replacing the Avalon Idea with speakers that could improve the low volume listening experience. I listen to 60 / 70db, I can afford to go up to 85db for very short time (neighbours).

I am also considering to purchase a Loki Max which I understood being quite a neutral EQ unit.

I have selected a few speakers which should match my musical taste based on what I have read:

- YG Carmel 2
- Wilson Sabrina X
- Vandersteen treo ct
- TAD ME1

I don't have the chance to listen to them except the TAD ME1 which I have enjoyed very much but not in my apartment.

Budget max $15k new or used.

I am looking for speakers sounding musical, with wide soundstage, not cold, detailed yet not analytical.

I mostly listen to classic rock, blues and jazz.

The system sits at the end of the long wall in a living room measuring 33x13ft, listening position 8ft from the speakers.

Unfortunately I have to face a tough WAF putting several limits:

- speakers must have a clean design, not black, not too hifi looking... and not too big
- distance from the wall behind the speakers 25cm

I don't mind changing amplifier if it will be necessary to match the next speakers.

I haven't found a preamp that I could consider a good candidate except a very expensive CSport featuring a loudness button which works very well (tested at Ana Mighty Sound).

I would much appreciate some advice from who knows well the above speakers or who had similar needs.