First of all, if you want to sing so that your neighbors hear it too (and if they get bothered, ask them to join the karaoke party!), you will need a microphone, a mixer, and some amplified speaker.
Here's a couple of good options we've tested and recommend.
Kbox Karaoke Kit
To get your karaoke-game up easily, we recommend you Kbox Karaoke Kit by Sunfly, which is an easy-to-use karaoke set, including professional-sound-quality microphones with tone and reverb options and necessary cables, and a mixer that transforms your computer, iPad or smartphone into a proper Karaoke system. With Karaoke Kit, you’ll only need computer, Smart tv, iPad, or a phone, speakers and an internet connection to get the singing out loud! And of course, Singa, so that you’ll have access to tens of thousands of songs.
There are plenty of other options and different karaoke sets available at our partners. Ask for more info and recommendations from the stores!