Moving into an apartment with wood joist floors - worried about neighbors hearing

Horn-based systems and dome other high efficiency systems tend to sound more lively when played at low volume.  Some also do a better job st focusing the sound energy at the listening position so that, they don’t have to played as loud.  Many of these systems don’t deliver very deep bass, and that is a plus in your setup.  An example of a good manufacturer of horn-based systems is Volti Audio.  High efficiency systems with great sounding speakers include the likes of Charney Audio and Songer Audio speakers.  Dipole speakers are also quite good in apartments because the front and back waves are out of phase and cancel at the sides; this becomes more pronounced as frequency drops so deep bass is attenuated the most.  The difference in sound that bleeds into other rooms between dipoles and othe types of speakers is substantial.  The dipole speakers I particularly like are the open baffle speakers made by Pure Audio Project.  They sound pretty at lower volume.

Loudness drops off quite a bit with increasing distance from the speaker; if you sit fairly close to the speaker it will sound louder.  Nearfield listening also reduces the impact of room acoustics on the sound.

OP, plenty of good advice previously given and, given the $'s one has to expend to live on the island, apply as much as you think you can apply....

(Just finished reading a note on some poor mortal paying 1,400$/mon. for 55 sq./ft.;
Now, Yes, NYC is an exciting city to be in, But....That's starting to rival those Tokyo 'hotels' that consist of a 'bunk-bed' module you crawl into....Por moi', NoF'nWay)

Throw a 'loft-warming party', and invite anyone above, below, and around you.

Don't know your new 'hood, but invest in some security features, as 15.5K$ speakers will make you an entrancing target, if not for the immediate neighbors, but one never can be totally clueless in Madhatterland....;)

Good luck, and enjoy the new digs....👍🤞🎉

As others have said, carpet the floor definitely.  Also 100% agree the Townshend platforms or Gaia feet, the latter on a granite slab. I definitely recommend near-field listening. A friend has a pair of huge high-end floor standers, on the end of a very high-end system, which by choice he sites literally 4 feet from his listening position.  It sounds absolutely incredible at low volumes.  

Slightly different take: cool your jets for a few weeks after move-in. Get the lay of the land, meet the neighbors without any insinuations of audio - get to know any who are willing to know you, as people instead of as assumed hobby obstacles to be convinced / woo’ed - for most people the former will go more naturally which is to say, less awkwardly. Use headphones during this time. I would not ask a neighbor I do not know well to do loudness / listening tests with me. That injects bias for concern in people and requires assuming they’re of similar personality / affability as you. It’s a risk, surely.

If your speakers energize the room for your boundary composition(s) / thickness / etc., no amount of wool or slab or otherwise will help unless you rebuild said boundaries - some room modes may be well away from your listening area and might not be on your side of the floor/wall, again depending on boundary composition / spacing. If it’s all wood and/or drywall, it’ll potentially be a real problem if you have a pair of intolerant ears opposite said boundary(ies).

During that initial “down time”, see what other sonic perturbations come from the building, the area, what times of day, etc. Educate yourself on relevant dB ordinance / statutes for your city / district.

I agree 60’s dB listening is not loud, so it will probably depend on how your bass peaks behave in-(and beyond)-room. I certainly wouldn’t sell a pair of speakers I really like for living a while in that type of place, at least not right away before I had lived in said environment and knew it as a resident vs. a brief visitor.

I'd invest in a Sound Pressure Level meter for your own use and to use in your downstairs' neighbor's place if things get ugly. I was a co-op board president in NYC a while, that's a great tool for handling complaints.