...bookshelf speakers that sound good at low volume...

I would try a Schitt Loki equalizer. Cheap and may work.  You will need another pair of ICs, which some people don't want to do.  I have one I would let you try if you want.  I live in NY as well. 

For what you desire a BBE 282 IR Sonic Maximizer would be perfect.
If you have no tape/processor loop you gotta get creative. Just like you would with a Loki. I have both and the BBE works better for "loudness."
There is also a dynamic range issue at suboptimal volume. A compander would help with that.

Yamaha R-N803 has loudness keyed to its room calibration system, a solid 100wpc amp, streaming, a DAC, phono, WiFi, all for $750.00. 

I just bought a pair of the newly released Elac Unifi 2.0 - $600. Using as TV speakers with a vintage 35w NAD receiver and music with CD player. In a similar sized room as yours. They’re 6 ohm @ 85dB sensitivity, but they play plenty loud enough. I wanted a 3-way speaker thinking we'd hear dialogue more clearly. These replace Dynaudio Emit 20 (4 ohm @ 85dB) 2-way and are a noticeable improvement in the midrange.
Out of the box they sounded flat and thin, but with about 60 hours on them now, they sound balanced and dynamic. Very strong bass output and midrange is excellent. High end is clear, not too bright. I almost can’t believe the bass output with bass-heavy music in that smallish room. They sound good at low volume although I do add a smidge of bass when played very softly. I sit about 7 ft away and sometimes read in there with music playing.
I even tried them with my 8w tube amp (no tone control) and found them to sound good with only a slight drop in bass response and dynamics. I’m very happy with them. Haven’t tried them yet in my bigger room, where I use either a Prima luna @40w or a Musical Fidelity @85w.

One of my local dealers recently picked up Fyne Audio. I heard the F500 Bookshelf. Excellent efficient speaker. 89db at 8 ohms. Price $895.