I always made sure to meet the neighbors above and below me. I gave them my phone number and said pls text if any issues with sound. I also did away with my subwoofer. I jammed music every night for three years and only had one complainer. She had a young child… fortunately she moved lol

Headphones

I live in a micro studio apartment.

I keep my speaker stands spiked, and they sit on two layers of carpet. No subwoofer.

Only once did a downstairs neighbor complain. It was a work night at 2330ish.

Hang them

Bass is usually the most problematic. Placement of speakers and seat should be biased towards being able to reduce the level of bass being generated. Yes, I’m thinking speakers against the wall/corner and listening seat against the back wall. Yes, this is rife with problems for you and the lumpy bass response this tends to net.

But using room boundaries does enable one to turn down the bass output which should lower the transmission thru the building.

Oh, those ‘out in the room’ systems your see pictures of do sound great but tend to end up with higher SPLs to get one to the fun part of music listening.

I guess it comes down to how much you want to sacrifice for being a good neighbor.

OP keep in mind that passive/DIY approaches to reducing sound transmission will at most net you 3-6db in some specific frequency ranges, but not much more.

Likely you will get a couple db reduction that might help reduce total transients I.e. kick drum

My priority is zero noise transmission to my neighbours

I live in an apartment and have been on both sides of this. As a neighbor, nothing is more annoying than hearing that “thud, thud, thud…” of too much bass slicing into my living room as if the walls/floor weren’t even there.

As a listener I used to get the occasional knock on the door / “It’s too loud / turn it down” visit.

I’ve long since given up on that and only use headphones for full volume listening. Whenever I listen on speakers, I have the volume low enough that I can barely hear it in one of my other rooms.

You can never really insulate from your neighbors in an apartment without serious sound insulation and strong, immovable walls, floors and ceiling such as a concrete apartment building with sheetrock inside.

The problem is that the deep bass that you enjoy from your system will transmit, through the air, and make your wood/sheetrock walls, ceiling and floor into resonant diaphragms.

You may be able to insulate your neighbors from higher frequencies with acoustic insulation, but the bass is problematic