I know the feeling i live in the Big Apple myself and fortunately was blessed with a new ac recently. Its much more quieter then my old one which might be one possible option is to just get a quieter air conditioner. I can actually listen to my speakers at nearfield positioning volumes without straining and the same at normal volumes. No speaker blasting around here since its not really my thing and i just find myself annoyed when i do it.
You could also go for some closed back headphones. One of the many i use to shut outside noise out is the KRK KNS-8400 and Koss Pro 4aat. Both very detailed with the Koss being more bassy yet defined in the treble department. Sound isolation is excellent at least on my big jawed mega sized forehead skull
With a quieter ac unit for my speaker listening i use some JBL Control One bookshelf speakers which are incredible for nearfield close up listening. I also use the Insignia NS B2111 but those are no longer sold though you could probably find them on sale online. Those are also incredible when it comes to highly detailed treble at low volumes with the option of more bass. They are front ported so one less worry when it comes to bass distortion or bothering the neighbors due to being too close to corner walls etc.
The JBL Control One was about 150.00 when i purchased it about three years ago.
The Insignia NS B2111 Bass Reflex speakers were $89.00 at Best Buy when i got them last year. I really lucked out on those since they were the last ones in the store.
