high-priority : /linux/audio : PT2

The answer I wanted was this one

Anyway

sudo setcap 'cap_sys_nice=eip' /usr/local/bin/renoise-3.4.2 
sudo setcap 'cap_sys_nice=eip' /opt/REAPER/reaper

then you can check

$ getcap /opt/REAPER/reaper 
/opt/REAPER/reaper cap_sys_nice=eip

$ getcap /usr/local/bin/renoise-3.4.2 
/usr/local/bin/renoise-3.4.2 cap_sys_nice=eip

Semi-relevant: There is this stackoverflow question and this unix.stackexchange question

See this linuxaudio article for info on CPU frequency scaling which you don't necessarily want.