If you are specifically interested in direct-radiators for music, I should think that you would also be very concerned about matching the timbre of the mains as closely as possible.

You might be surprised how much you would enjoy the QS8's. At any rate, I can't imagine being able to do better for the money and sonic compatability than the Axiom bookshelves if you are set on monopoles.

Based on what you've said, I would take a chance on some M22's.

bibere usque ad hilaritatem