Audacious is an open-source music player, having the features of a modern music player, including support for audio effects, equalizer, lyrics and plugins, visualization, support for Winamp skins and support for playlists organized in tabs.
Starting with Audacious 3.6, the software adopted GTK2 by default, while at Qt5 version is also available via the settings menu.
The latest version available is Audacious 3.7.1, bringing bug-fixes only.
Installation instructions:
Audacious is available via some third party PPA, so installing Audacious and keeping it up to date on Ubuntu 16.04 Xenial Xerus, Ubuntu 15.10 Wily Werewolf, Ubuntu 14.04 Trusty Tahr, Linux Mint 17.x, Elementary OS 0.3 Freya and other Ubuntu derivative systems is piece of cake.
What you need to do is add the PPA to your system, refresh the local repositories and install the audaciuos package:
$ sudo add-apt-repository ppa:nilarimogard/webupd8
$ sudo apt-get update
$ sudo apt-get install audacious audacious-plugins
Optional, to remove audacious, do:
$ sudo apt-get remove audacious audacious-plugins