An amplifier is integrated into the device. An audio amplifier takes a small signal and makes it bigger without making any other changes in it which results in better sound, so any sound source can be connected to speakers.
65% have it
11. supports Bluetooth pairing using NFC
Device supports fast Bluetooth pairing using NFC so it can communicate with other devices over Bluetooth. You can fastly pair devices without entering a code by simply holding one device next to the device with which it is to be paired.
27% have it
12. has a subwoofer
Devices with a subwoofer have a higher quality, deeper bass.