Bose has recently introduced a new product:.
Bose SoundTouchWireless Link Adapter. It's probably not the cheapest option, but I think it's exactly what you need.

If the stereo system has an output connector, e.g. cinch, you can connect it to the line-in of the Bose. The following cable is usually used for this purpose: Audio cable, 2x cinch plug to 3.5mm stereo jack plug.

I would always consider whether I really need one :). Do you really need CD players nowadays?