BEST SPEAKER THAT COMES TO LIFE AT LOW LISTENING LEVELS

Speakers with high efficiency (90db) will help however a combination of amp/preamp with low impedance can produce louder sound at lower volume. I can have low volume which sounds loud with my combo of ARC VS115 amp and ARC LS17 preamp with Revel F32 speakers (86db efficiency)

I listen at the same low levels. I have QLN Prestige 3 speakers with a Rega Aethos integrated amp, and they sound great at lower volumes.

At low levels like that I wouldn’t spend as much as you’re budgeting and instead go with a 8K / pair if Dynaudio Heritage Specials plus a a REL sub and you’d be set and save 4K.  The dynaudio are excellent at low volume levels 

I have no dog in this fight, since what I’m about to recommend is quite contrary to what I normally design. That said ...

A full-range driver with a tonality YOU like. They are all colored, none are neutral or flat, but some are really pleasing at conversational or background levels. Lowther, AER, Feastrex, etc. etc. Backhorn loading sounds best with these guys, not a conventional box.

Why? Well, a problem with most multiway speakers is dynamic tracking. It shouldn’t be, but it is real and very audible and annoying. Subjectively, the drivers fall "out of sync" with each other at low levels, and the speaker sounds disjointed and very artificial and "hifi". What you want at modest levels is the best table radio you’ve ever heard, which is where full-range drivers come in.

The out-of-sync problem is worst with complex low-efficiency speakers. They sound great at 85 dB or more, powered by 300-watt amplifiers, but turn it down to background levels and all you hear is an indistinct grumbling, hardly music at all. Simplicity is your friend here; a basic 2-way will sound better than a 3 or 4 way, fewer drivers will sound better than many, and a full-range driver that falls apart at 95 dB will be a real charmer at 60 dB.

What you want is crystal clarity at conversational levels ... and yes, a fully restored Quad ESL57 is one of the best speakers ever made for those levels. Very low distortion and perfect square waves. The most pure and honest tonality ever. Perhaps best of all, there is NO CHANGE in tonality over the 50 to 80 dB range. Some of the full-rangers (AER, Feastrex) are like that too.

As for amplifiers, Small Is Beautiful. No more than two transistors, or two power tubes, per channel. Maybe even single-ended if you’re into that sound. No Class AB. You want Class A, whether transistor or tube.

My Magnepan 1.7's sound very good at low levels.........