DC 5V to Audio Line Level
I'm going to make an assumption here because you didn't provide enough information.

Specifically, I assume that this is an analog signal that ranges from 0V through +5V.

The solution is simple.  All you need to do is to capacitively-couple the signal from the controller output network into your destination device.

I'm going to make a couple more assumptions here:

1) The output impedance from the controller and its output network is fairly low.

2) The input impedance of the device that you are trying to feed is fairly high.







simulate this circuit &ndash; Schematic created using CircuitLab

I'm showing a polarized capacitor because that is the most common.  The (+) side of the capacitor goes to the node with the most positive (highest) average DC voltage.  That would be from your microcontroller: the average voltage is about 2.5 Vdc assuming that the signal swings all the way from 0V to 5V.

It's really that simple!