Amarok does not have clear maintainers of all parts of the codebase. The current list of components and maintainers can be found here: http://community.kde.org/Amarok/Development/Components

You are welcome to work on any part of it provided you coordinate with others working in that part.

If you need to contact someone about a particular part it is best to contact the developer mailing list at amarok-devel@kde.org or the assignee of the corresponding component on http://bugs.kde.org directly.