Would also be great for maximizing audio quality.

Right but isn't the upstream kernel now where the RT development is happening? If there is something we can merge into the kernel, please show me :D It's important for creators

My understanding is that you can patch existing kernels.
The Real-Time Linux Wiki should give an overview.
The RT PREEMPT HOWTO should do the trick.

Looks interesting what the Arch-based AudioPhile Linux is doing: http://www.ap-linux.com/

This is an absolute must have for music production. Currently having to resort to 10ms delays and at times to 20ms even on high-end hardware. Would be amazing if implemented.

It's a matter of having a kernel built with this scheduler enabled (if not patching) isn't it?

It seems to be an out-of-tree patch still:

https://rt.wiki.kernel.org/index.php/Main_Page
https://www.kernel.org/pub/linux/kernel/projects/rt/

Here is a torrent link to download Audiophile Linux if someone wants to investigate and find out if there is anything interesting to learn from it.
This should potentially be faster than their free hosted download.

AudioPhile Linux V4.0 ISO

Is an out-of-tree patch still interesting for an optional kernel?

I have no interest in an out-of-tree patch. Let's wait for things to get merged.

Why wouldn't an out-of-tree be interesting? It seems that patch is used in other distributions to provide a realtime kernel. Why not in Solus?

In T3662#130637, @SolarLiner wrote:

Why wouldn't an out-of-tree be interesting? It seems that patch is used in other distributions to provide a realtime kernel. Why not in Solus?

Because out of tree patches are a hassle. They are rarely up-to-date with the kernels we ship which means either holding back the kernel update (not an option) or having to manually port the patchset every release instead of waiting on someone else (not an option either). I'm not taking on that maintenance burden when people are actively working to get them merged into mainline.