Converting USB speakers to Bluetooth

I have a set of the original Sound Sticks, and they still sound beautiful, but we don't have a desktop machine any more, and it's not exactly practical to carry them around with the laptop. It breaks my heart to think that these lovely speakers might amount to a set of really pretty paper weights.

I have a small Bluetooth receiver with both 3.5mm and RCA out. The speakers have their own power supply. How can I get them what they need signal-wise to work with this setup?