Guiseppi,

 For sound cards, it is important to look at the specs but there are really only a few that matter for amateur use. PCIM  and optical digital  I/O are not need but are a common feature.  Terrific for home theater use though. Those require outboard hardware to work.

The higher sample rates are better for digital modes. It actually does make a difference.  A card with 24 bit or 32-bit data streams will give better performance than a 16-bit stream. 192k  is better than 48k and so on.

  The higher rates for some applications determine the bandwidth of SDR rigs and a well as digital modes. Never use a sample rate less than 48k.  96k or 192k are better options. There are a few cards that go higher than 192k. Those that do are very expensive. The spec that means the most though is the S/N ratio. Most onboard soundcards ( those built into the motherboard)  are horrid to say the least. usually in the mid 90dB range. A plug in card, has better isolation to reduce noise. Higher S/N ratios are better. I have an ASUS card with an S/N of 118dB. There are a small few that are upwards of 124dB. The S/N ratio is usually the determining factor as to cost.

 Why does any of this matter? If your into digital modes like JT65, FT8, etc. it helps to decode the really weak signal in the noise. The higher the S/N ratio the better the weak signal can be decoded, and the higher the sample rate the wider the received bandwidth for digital modes and SDR rigs. If you want the best digital mode performance, use a soundcard that is not built into the motherboard for SDR and digital modes.

 Most newer SDR use VAC or some version of a virtual cable. Those still link to hardware. Make sure your Virtual sound cables are up to date as well. Be it VAC or Burells VBCable or Banana mixer programs. They link hardware to software, and error introduced by hardware get transported as well as the data degrading performance.

 Last. Whatever soundcard you use, and virtual cable you prefer, make certain, the sample rates and stream width match across the system. If your running a 24bit 96k sample rate on your sound card, make certain your virtual cable and mixers are also running 24bit 96k, as well as your digital mode program, be it FLDigi, HRD, DXLabs, etc. If running a different rate like 16bit 192k then all of your other systems handling your sound throughput should also be 16bit 192k. Mixing sample rates introduce lag and error into your system.

   Jeff