Limiter, compressor, reverberation, equalizer and auto volume effects for Pulseaudio applications.

Audio Overload emulates the sound hardware of vintage consoles and computers, allowing you to listen to completely authentic renditions of classic video game tunes. Audio Overload does not play music from arcade games; for that you should use M1.

This program is an audio player, written with the help of the Qt library. The user interface is similar to winamp or xmms. An alternative user interface is also available.

qmmp.ylsoftware.com
sourceforge.net/projects/qmmp-dev
qmmp-modern
An attempt to support “modern” Winamp skins in a Qmmp plugin.
Nuvola (Linux) Apps are web apps running in Nuvola Apps Runtime that provides them with more native user experience and richer desktop integration features than standard web browsers can offer. Nuvola specializes in music streaming services and offers background playback, handling of media key, integration with media player applets, Last.fm scrobbling, lyrics fetching, and much more.
Although Nuvola should work in all Linux desktop environments, we currently test only GNOME (Ubuntu, Fedora), Unity (Ubuntu), and Pantheon (elementaryOS). We hope to explore other desktops in the future.
Volumio is an headless audiophile music player, designed to play music with the highest possible fidelity. Volumio runs on most embedded devices (Raspberry Pi, UDOO, Odroid, Cubieboard, Beaglebone, Pine64, Allo Sparky…) and on any ordinary PC (x86).
Volumio is a free and open source Linux distribution, designed and fine-tuned exclusively for music playback. It runs on a variety of devices, typically small and inexpensive computers like the Raspberry PI, but also on low power PCs, notebooks or thin clients.
By flashing (installing) Volumio on any of these platforms, it will then become an headless audiophile music player. Headless means that the only way to control it will be with another mobile phone, computer or tablet.
This is made possible by Volumio’s User Interface: a web applications that runs on any device with a browser, and that allows for an easy and intuitive control of your playback sessions. All communications between the web app and Volumio will happen through your home network.
Smart Mix Player is a free auto disc jockey player for Linux and Windows. It plays audio files as a non stop mix, but not in the way that traditional auto DJ software does!
Most of these players mix songs together at the end of a song with a simple fade out and fade in. Smart Mix Player goes a big step further and mixes like a real DJ!

This is the synthesizer plug-in Surge which Claes Johanson (@kurasu) previously sold as a commercial product via the company vember audio.
As he is too busy with other projects and no longer wanted to put the effort into maintaining Surge across multiple platforms, he decided to give it a new life as an open-source project.
It was originally released in 2005, and was one of Claes’ first larger projects. It is reliable and sounds great.

An open-source cross-platform audible audiobook manager. With over 250 stars by github developers, OpenAudible is the trusted audio book content manager.

DeaDBeeF (as in 0xDEADBEEF) is a modular audio player for GNU/Linux, *BSD, OpenSolaris, macOS, and other UNIX-like systems.
DeaDBeeF lets you play variety of audio formats, convert between them, customize the UI almost any way you want, and use many additional plugins which can extend it even more.

deadbeef.sourceforge.net
deadbeef.sourceforge.net/download
deadbeef.sourceforge.io/plugins.html
play.google.com/store/apps/details?id=org.deadbeef.android
CUI ~ A faceted library browser plugin for Deadbeef. Columns-UI-like
github.com/VirInvictus/deadbeef-cui
github.com/topics/deadbeef
github.com/topics/deadbeef-plugin
en.wikipedia.org/wiki/DeaDBeeF
Pulseaudio Crossover Rack is a program to design and implement multi-way speaker crossovers using any linux powered computer with a multi-channel sound card and a running desktop environment which uses Pulseaudio as it’s sound backend. It also uses a set of LADSPA plugins, namely ladspa-t5-plugins for the heavy lifting of DSP/audio processing. It’s written in python3 and uses QT as the windowing toolkit.

It’s time to ditch Skype and TeamSpeak. All-in-one voice and text chat for gamers that’s free, secure, and works on both your desktop and phone. Stop paying for TeamSpeak servers and hassling with Skype. Simplify your life.
Airtime is an open source application that provides remote and
collaborative automation of a broadcast radio station.Major features:
- Web-based remote station management. Authorized personnel can add
programme material, create playlists or smart blocks, and stream in live,
all via a web interface.- Automation. Airtime has a scheduler function that enables users to
create shows with content for playback at the exact date and time specified.- Playlists, smart blocks and remote stream URLs can be used multiple times.
- Solid playout. Airtime uses the open source Liquidsoap streaming language for reliable and precise playback to multiple outputs.
- Open, extensible architecture. Stations are free to extend and alter
all parts of the program code, under the GNU AGPLv3 license.

www.sourcefabric.org/en/airtime
en.wikipedia.org/wiki/Airtime_(software)