Recommendations for speakers that sound great at lower volume levels.

What you need cannot be achieved by ANY speaker (except a subwoofer).
What you need is an amplifier with the good old fashioned loudness control.

Low noise, low distortion, electrical synergy, a quiet room.  The whole signal path is relevant for engaging low level music.  Don’t just blame your speakers.

Big.high.efficiency.speakers…

Got a pair of Cornwalls specifically for this reason. 
Also have a pair of ESL-57’s which also, as it has been stated above, sound lovely at low volume.

Big speakers that are high efficiency do help in low volume listening.

Not full-range…but I’m partial to Dynaudio Heritage Specials. 

Quite true @terry9. That's a result of the Fletcher-Munson characteristics of human hearing, not the Quad ESL itself. Of course, a speaker with more bass output at higher levels will have that at lower levels too, relative the Quad.

The best late night low volume listening I have had was with Magnepan MG-20..............but it was also a heck of a system...CJ ART, etc.  I have had Martin Logan, Advent, Vandersteen and others.  The myth about efficiency and low level listening is just that. 

you need a big subwoofer (it will add bulk, but not volume) + a good preamp ...

Spatial Audio Labs X3, and X 5 open baffle speakers.

This afternoon I was listening to my Quad ESLs at very low volume: pure magic. BUT not bass you can feel - I think that's impossible at low volume.

Quad ESL.

I have Salk Exotica Raal monitors.  I can highly recommend them for low level listening.  I marvel at the sound every day.  I listen a good portion of the day while working.  

I owned the Harbeth SHL5 Plus and earlier versions of the SHL5 and they all sounded great at low volumes. I actually bought them for that reason. The issue is more likely to be your amplifier. Harbeth's, when used with SS amps like Ayre, Aesthetix, Naim, Musical Fidelity and many others excel at low volume. 

I've have never heard a Harbeth speaker that sounds good with any tube amplifier though many others will disagree. If you like your amp you should work with a Line Magnetic dealer to find the right speaker for your requirements. You might also find a dealer who would loan you a SS amplifier to try in your system to see if the Harbeth's might actually meet your low volume needs.

Good Luck!

+1 on the LS3/5a... had an 11ohm set of Rogers from the mid 80s and just loved them. Wish I still had them... playing a set of Equation "7" these days that are just incredible in my kit. Listen late night in a dead quiet room and paired with a Cary tube amp and Manley Shrimp tube pre they are incredible. Won't find much on the web and the distributor in Canada, Mutine, got beat up pretty good on here a while back but they are special. All hand made in Belgium with the finest components and internal wiring. Had no idea what to expect other then they mated well with
low powered tube gear. The "7" were the bottom end of their line and retailed for $3K in '05. Said to be perfect symetry between Equation speakers and Audiomat electronics; the Arpege integrated specifically. Have heard the Audiomat gears and sadly never got the chance to pair them togther. Anyway, fabulous at low volume - everything's there full and robust. A real treat if you can come across a set. Maybe $13-$1500 depending on condition; worth every penny. 

I think the persona B could be on the list. 

I’ll give another endorsement for British mini monitors. I have small to smallish listening rooms. I also listen more times than not,at low volume. My Graham Chartwell LS3/5’s do a wonderful job at low volume. They soundstage freakishly well. I also run them with a couple low power First Watt amps. They will always be in the rotation for me. The great thing with these mini monitors,is you can flip them if you don’t like them,and probably break even at worst. 

Ha! I've seen that review. Very thoughtful evaluation and presentation.

I have owned the Harbeth M30.1,C7 and the newer P3ESR. In my 20x15 size listening room using tube amplification the original P3 just sounded better. I always prefer a sealed speaker better than any speaker with ports. BTW, I have tried many different speakers and I always go back to the P3. I have owned five pairs so I learned my lesson not to change to other speakers just because they are pricier and bigger!
This guy likes them like I do!
https://www.youtube.com/watch?v=mqFIaiPT_kY

In general, high efficiency speakers sound good at lower volume levels. 

Yogiboy - I've wondered about the P3 compared to SHL5. Can you offer more detail about the p3 and why it's your pick among Harbeths? Thanks.

+ jjss49
Any Ls3/5A design would fit the bill. I’ve owned quite a few and the Harbeth P3 is still my favorite of the lot. I have also owned larger Harbeths and IMO the P3 is the pick of the litter. And I don’t use a subwoofer!

harbeths are actually considered to be very good at low levels and nearfield

if you like the harbeth sonic palette maybe try a smaller model... c7, mon 30, p3?

of course the famous bbc ls3/5a was the original brilliant nearfield mini monitor, with bumped up midbass to fool the ear at lower volumes into thinking it is more full range than it is... of course the treble and midband are beyond reproach

excellent related or descendant speakers of small form factor for lower level or nearfield listening from atc, proac, spendor, kef, sonus faber, and so on - there are many many out there, with different sonic presentations