Quoting Grammostola Rosea <rosea.grammostola(a)gmail.com>om>:
I've an maudio keystation usb midi keyboard... How should I connect it?
Just USB or also MIDI cable?
I don't know if USB-MIDI works in linux, and in this case in
particular, so use the old round MIDI jacks/cables.
How do I know if I have the rights for
/dev/snd/midiC0D0
'ls -la /dev/snd' should say something like
crw-rw---- 1 root audio 116, 16 mar 16 08:56 midiC0D0
so in this case you should either be root (not recommended) or member
of the audio group to have the rights (rw) to use the device.
If you see your username instead of "root" there, you're fine.
If not, run 'groups' to see if you're a member of the audio group and
if you aren't run 'usermod -G audio -a your-username' as root