FreqCheck is a sine wave generator to create audio curves. With appropriate use, a kind of audiogram (auditory curve) is possible.

An MPD frontend with delusions of grandeur.
It exists to sate my need for something that’s got the bling and the features to back that bling up.
libadwaita UI for most MPD features, from queue reordering and ReplayGain to crossfade and MixRamp configuration.ncmpcpp-inspired keyboard shortcuts.
soundKonverter is a frontend to various audio converters.
The key features are:

github.com/dfaust/soundkonverter
github.com/nphantasm/soundkonverter
store.kde.org/p/1126634
GSonic Reference is a high-quality speaker and room correction tool that generates precision FIR correction filters from in-room measurements. It combines spatial measurement averaging with advanced filter generation to deliver studio-grade correction for any stereo listening environment.
github.com/ObsessiveCompulsiveAudiophile/GSonic
hydrogenaudio.org/index.php/topic,129351.0
This application is very useful for all music collectors who are looking for the “perfect” record. In fact, this application allows you to find, through the well-stocked music catalog “discogs.com“, the prices of the respective vinyl, calculating in real time minimum, average and maximum price of those who at this moment are selling just the vinyl you’re looking for.
In addition to the price you can obtain vinyl’s code, year of publication, country of origin and music label. This application also works with cds, tapes and also digital files.
Requires a Discogs account.
play.google.com/store/apps/details?id=it.finproductions.vinylprice
An application to download podcasts. Enter RSS feeds manually or import OPML file to download the latest podcasts.

github.com/r57zone/PodcastEasy
sourceforge.net/projects/podcasteasy
KMix is a sound channel mixer and volume control.

apps.kde.org/kmix
github.com/kde/kmix
invent.kde.org/multimedia/kmix
docs.kde.org/trunk_kf6/en/kmix
userbase.kde.org/KMix
JuK is an audio jukebox application, supporting collections of MP3, Ogg Vorbis, and FLAC audio files. It allows you to edit the “tags” of your audio files, and manage your collection and playlists. Its main focus, in fact, is on music management.
Features:

apps.kde.org/juk
github.com/KDE/juk
invent.kde.org/multimedia/juk
en.wikipedia.org/wiki/JuK
AudioTube can search YouTube Music, list albums and artists, play automatically generated playlists, albums and allows to put your own playlist together. It is adapted to mobile phones and desktop computers.

apps.kde.org/audiotube
github.com/KDE/audiotube
invent.kde.org/multimedia/audiotube
Audex is a CD ripper application. It lets you extract the audio from your CDs to let you listen to them on your computer and your other devices. It includes CDDB and MusicBrainz integrations to fetch the metadata and covers for your CDs if available.

apps.kde.org/audex
github.com/KDE/audex
invent.kde.org/multimedia/audex
userbase.kde.org/Audex
en.wikipedia.org/wiki/KDE_Gear#Playback
K3b was created to be a feature-rich and easy to handle CD and DVD burning application. It consists of basically three parts:
- The projects: Projects are created from the file menu and then filled with data to burn
- The Tools: The tools menu offers different tools like CD copy or DVD formatting
- Context sensitive media actions: When clicking on the icon representing a CD/DVD drive K3b will present its contents and allow some further action.

apps.kde.org/k3b
github.com/kde/k3b
sourceforge.net/projects/k3b
snapcraft.io/k3b
en.wikipedia.org/wiki/K3b
K3b Themes