Let's say I have a mic-level signal running on an XLR cable - a vocal microphone going to a mixer or preamp. I'm looking for the simplest way to add another mono audio signal to the line.
I've got a sine tone generator and want to "add" it to the microphone signal (and still hear the microphone). The sine wave is coming from a DAC and will be converted to a mic-level signal.
Attaching the DAC straight to pin 2 or 3 of the XLR connection seems to work, but there must be another way that is more proper, is there? Do I need to balance the signal and connect it to both pins 2 and 3 of the mic signal? Or somehow protect the DAC or microphone from one another? Audio quality is not super important since it's just a tone. I'm more interested in the lowest parts count solution.