Command not found

Now that I have one of those speaker systems 5.1 connected via usb, a fast acquisition until I bought a real amplifier. Well I’ve connected it on my laptop and of course it works under ubuntu but … Amarok does not detects well the device, although it detected once, but never again
I’ve searched for another player *with* equalizer and installed Exaile, seems that it is written in python but I think it doesn’t follow at all python phylosophy, It is very complicated, too things, queue, playlist, list of files in folder, Aaaah! One thing is quite good: tagging, but difficult to understand its interface and a bit broken. And on my system, something is broken in the music library, I’m getting this pretty WTF window: