What in general, is the difference between a Audio ADC and an ADC, which has a similar sample rate (up to 100khz in my example) and a similar bit depth (12 bit in my example). I would like to use the MPC3208 in my circuit to convert analogue signals from a mic preamp to a digital signal. Do you think I can use it as a audio ADC? Subquestion: Those 12 bit should be enough when not doing expensive editing afterwards, right? I don't expect a superior HiFi sound, just one that sounds 'good enough' for consumers.
The important thing audio ADCs do is blocking higher frequency signals before sampling. An actual high quality audio ADC these days these days usually contains oversampling circuitry and digital filters since you cannot do the filtering job with analog filters alone at sufficient quality.
12bit of audio gives you 72dB of signal above quantization. You'll need a lot of noise shaping to make the quantization noise innocuous, not having any obvious relation to quiet signals. Good tape drives are in that range, and they degrade "graciously" both with regard to overdriving your signal and having it fade into the noise floor.
So don't expect things to "just work" with specs as confined as that.