Determining the ADC's of a sound card.

We would need to know the exact model as ST has tons of cards.

Now onto what we can determine.

ADCs are analog to digital converters, they would be used for lets say the mic and line-in ports.

Now just because you have mic and line in does not always give you the answer either. Some cards will use just a 2 channel and software will allow mic OR linein to be used, but not together. This seems to be a trend to cut costs.

Are you looking to record from more then one source?

Not ALL ADCs are just 2 channel, and with some work, you can probably make a 4 channel one take 2 operate sources. I am NOT an audio engineer so do not quote me on it  

The question I think you may have been asking, would be how many DACs the card has. The Digital to Analog Converter are what turn the digital audio signal to something yours speakers can play back(a nice AC sound wave). This depends on the number of channels needed. A single chip DAC can with ease handle those 4 channels.

Now with integration, you can actually combine many of those parts right into the sound cards chip. With modern integration you get the sound processor(it is a dac in its own right),dacs, adcs and any opamps you need to boost the DAC signal to line levels plus all of the required filtering for audio all in one little chip.

Is technology not just great