I have a PC with a USB DAC that has bluetooth, and I wonder if there's a way to receive the bluetooth stream on my iMac. Basically I'd like to use the iMac as a bluetooth speaker.
You need a Bluetooth audio receiver. Whether it will work depends on if how your model iMac accepts audio input, e.g. USB? Audio-in port? You’ll also need a software program that can capture the input audio.