It is possible to disallow the use of analog outputs, although this has yet to be implemented.
There are already plans to not allow analog output for "Copyright Protection" reasons.
This extension was used for analog output from the video card, which was then routed through the system board to the system's own monitor output.
The concern being that unprotected analog output is open to piracy.
It generates one analog output (16-bit dynamic range) from a single serial input, the sound data containing a 10-bit mantissa and 3-bit exponent.
This ensures that an analog output is an accurate representation of an input, typically with higher amplitude (amplified).
The units also had an optional analog output.
There is an intermediate device, a 'hybrid' computer, in which an analog output is converted into digits.
AC97 defines a maximum of 6 channels of analog audio output.
What we hear in speakers is an analog (current, voltage or electric charge) output of the signal.