I myself have been using KMix instead, because changing application volumes from applet is a must have for me. But KMix system tray popup doesn't really integrate nicely into Plasma, so I finally decided to switch to plasma-pa and implement those missing features.
My goal is to achieve feature parity with KMix, so that I and all Plasma users can switch to plasma-pa without missing anything.
First and most important thing for me is the ability to change application volumes from applet. That's actually the main thing I expect to be able to do from the applet as I manage volume of my sound card with global shortcuts.
There are now two tabs in applet, one for managing volume of devices and one for applications. Application streams will also display icons for easier navigation.
Another useful feature if you have multiple sound cards is to move streams to different devices. In the first draft it was possible to do so in both applet and KCM, but it was then decided to have this functionality only in KCM to keep the applet simple.
You can now also choose your default device which will be used for applet icon and global shortcuts.
Some laptops have microphone mute button, it will now be possible to assign this button to mute microphone global shortcut. Ideally it should work without any settings (if the button sends XF86AudioMicMute key event) and is the case on my laptop. Global shortcuts for changing microphone volume will also be available.
|Microphone volume OSD (icon is not final)|
And finally, you will also be able to change volume of notification sounds from KCM. There is a lot of changes that will make the audio management in Plasma better.
One thing that users are requesting is volume overdrive - ability to increase volume over 100%. That's something I'd like to eventually have, but I'm not sure if it makes it into the new release.
That's it, I hope you'll like all the new features (and also fixes) that are coming with Plasma 5.7!