Comment 2 for bug 152487

After a full day devoted to solve this issue, I found that it is utterly unnecessary to compile+install from source or for that case (re)install anything.

Ubuntu devs has chosen to not include the jack output plugin because it needs a package from universe to build it. (It's a pity that this affects so many of us that has universe enabled!) All you need to do is to get hold of a suiting compiled plugin.

Compiled plugins for i386, installation instructions and more available here: http://ubuntuforums.org/showthread.php?p=1556348#post1556348

Listining to my amarok tunes and playing on my keyboard now. :)

Hope this works for you too!