at the moment Roon Rock is installed on an intel 6i5 nuc. It works nice, press button, it starts up, press button, it shuts down. Now there is one issue, I like to have HQ player installed too, but that does not work on Roon Rock.
So next to try a normal linux distro, install Roon and HQplayer and it is all set. But to reach this I like to have a distro that behaves like Roon Rock, press button start up, press button again, shut down. Tried already Ubuntu and Kubuntu, issue is, it keeps hanging at the shut down and need to attach a screen and keyboard to shut it down.
Are there distro’s that shut down with one click on the power button?
that is what I tried in Kubuntu, did everthing that was proposed and it was still hanging, something was overruling my shut down settings, work with linux since 2003 and this specific problem I could not find the reason why the kubuntu still did not shut down by pressing the button.
My Pinkfaun streamer works on Audiolinux and does exactly what you want.
Cannot help you xith any configs, as unfortunately Iam still Linux agnostic
Dirk
yes, pink faun did implement their own software to audio linux, the only one. I cannot use that specific designed software because it is dedicated for Pink Faun. The Normal Audiolinux distributions, I have no idea which licence to buy, It must be great, sadly have no idea how to start and what licence I have to order. 
I honestly brlieve there is only 1 major Audiolinux license that you can buy.
Look at Audiolinux.com , you can definitely ask for help there.
On the Computer Audiophile forum the author is a registered user called Hifi25nl if I am not mistaken
I will give this a try and will buy this licence. Many thanks 
i have no answer for a power off button.
but i have configured ssh on my server.
and there are many apps for ios (and i expect also for android) that can send commands via ssh to the linux server.
i’m using the app sshutdown. with this i switch off my server.
it’s possible to define further virtual buttons for other commands.
AudioLinux (Headless or LXQT).
Update about this, and I think I found a distro that works. It is called Ubuntu Studio. This distro is so good and easy to install I can recommend this
installing is easy, don’t forget to check at the installation that 3rd party software is installed and to change that at startup a login is not needed
and one important thing, after installation you need to make your own root password, it is a strange Ubuntu characteristic not doing this at installation. To do this: open the terminal and then type sudo passwd
This one really surprised me, power off with the button was a small change in the top right corner it works. After a few minutes, the screen will be locked, that one can be adjusted in the screensaver settings.
Installing Roon was very easy, I never had this before that it instantly installs the bz2 file. After unpacking you only have to open the installed ./start.sh file, to make it boot at startup a small settings change need to be made, and thats it
At this point you have a linux distribution that works the same as Roon Rock, including radio, and as bonus a full working computer, you can send mails, use office, print, etcetera, and the possibility to install HQ player!