Which (portable) program is to recommend to manage music (files)?

Good luck finding portable versions.

You can try "PortableApps" website:
http://portableapps.com/

They create portable versions for programs that aren't normally portable.
Only for freeware versions. They won't deal with pirated programs.

And I think they mainly deal with programs that have open source code. Which would make it a lot easier to create a portable version of the application.

Thank you very much!

Nemp is a portable app. :)
http://www.gausi.de/nemp-en.html

Thank you, Zoran, I will try it.

I am trying it at the moment, yes, seems to be a very nice player / manager.

I'm glad you like it Biffos, admittedly it take a little getting used to but it does have some really nice features. :)

Yes, nice features, quite many options, indeed, that takes a time to get to know it, but the assistant is very convenient (which lets you chose not to edit / change your music files by Nemp) and its music library is very nice.