Well you definitely do need a DAC at the receiving end. Some receivers come with bluetooth adapters, but other than that I don't know of anything to attach to a receiver for a wireless signal.
If you want to send a DIGITAL wireless signal you need a DAC at the receiver. Also if you are transmitting wireless audio digitally, your computer DAC isn't doing anything, since it is a "digital to analogue converter" and you are not converting to analogue in the computer, but at the receiving end. That being said, you obviously don't want to send an analogue radio signal, since you will pick up all sorts of interference.