AmpControl, ampcontrol, and ampctrld

AmpControl is a Java desktop application to control an Onkyo receiver or amplifier over the network.
ampcontrol is a Node.js application which fulfills the same purpose, but comes with a web frontend.
ampctrld is a re-implementation of ampcontrol in pure C.
Currently, all three allow you to

select the input source
adjust the volume level
mute/unmute audio
power on/power off the unit.

In addition, ampcontrol and ampctrld have controls for media streaming.
ampctrld allows you to assign user-defined names to the input sources, and can listen on multiple addresses, i.e. on an IPv4 and an IPv6 at the same time.

ampctrld

Compile

tar xf ampctrld-2.tar.bz2
cd ampctrld-2
make
make install

You now have /usr/local/etc/rc.d/ampctrld on FreeBSD, and /lib/systemd/system/ampctrld.service or /etc/init.d/ampctrld on a Linux with systemd or OpenRC, respectively.

Usage

ampctrld version 2

Usage:
ampctrld [-d] [-i <id>=<name>] [-l <address>[:<port>]] [-p <pid file>]
         [-u <user>] [<amplifier>[:<port>]]
ampctrld -a
ampctrld -h

  -d                       run in foreground, and log to stdout/stderr, do not
                           detach from terminal, do not log to syslog
  -i <id>=<name>           assign <name> to input <id>;
                           may be specified multiple times
  -l <address>[:<port>]    listen on this address and port; a maximum of 16
                           addresses may be specified; port defaults to 8082;
                           default: 0.0.0.0:8082
  -p <pidfile>             daemonize and save pid to this file; no default, pid
                           gets not written to any file unless <pidfile> is given
  -u <user>                switch to this user; no default, run as invoking user

  <amplifier>[:<port>]     connect to this amplifier; default: onkyo:60128

  -a                       show default input names
  -h                       show this help ;-)