Merging AC & DC Signals

How can I merge an AC audio feed and a headset cable into one stereo male jack going into a DC device? I believe that is the issue I’m dealing with. For more info the post listed below may help. Thanks!

Probably something like this:

Here’s the forum topic that this image came from:

Even with a suitable battery supply, the microphone signal may still be too small to drive your stomp box properly.