A sound card that samples at 48KHz should be able to look at signals as high as 24KHz, a card that samples at 192KHz should be able to see signals as high as 96KHz.

Sadly some cards do not follow that rule but instead have fixed filters in front of the card so even if you go to the high sampling speed the bandwidth of the card is limited to as an example 20KHz, such a card would not be a good card for SDR work.

Always check the manufacturer's sight for data to see what the front end bandwidth is for the different rates, it should be 1/2 the sampling speed.