Hi,
Like Sassler I suggest the MADDE thread.

Your project sounds complicated enough that using Qt is a good option. Plus the Qt libraries will help with a lot of the things you want to do.

I did a small Phonon test a while back, just to see how Phonon works: open two songs to play at the same time. (don't mind the initial garbage on the first player text area, just testing stuff)

Warning, it's only a test and I'm not a proper developer.