Sound card for recording audio
The number of channels mentioned in the products you linked refer to output channels. A Dolby 5.1 system has 6 speakers (center, rear R/L, front R/L, subwoofer), thus 6 channels.

What you're looking for ist usually called audio interface and mostly used in music production studios. Manufacturers are M-Audio, Roland, Behringer (cheap), Focusrite and many more. You can get an overview here. From your previous question I assume that your application is speaker localization. Therefore you probalby don't need high-class converters and pre-amplifiers. If you're planning to use Linux it will reduce your choice.