Thats new to me. Is there any chance to see the differences? I have no idea if its really worth to worry about that
-With appropriate Sound cards, processing of audio is done on a separate Audio Processor. This is hard to argue as not being a good thing, since it frees up the main processor for other tasks.
- To what extent? Particularly prevalent for Game-based Audio and certain movie or video features such as 3-D positional Audio, EAX effects, surround sound, 3-D Virtualization, etc. EAX and similar post-processing effects are the most common and perhaps taken for granted the most. Game characters moving through a cave may make all sounds in the cave "echo"; underwater and the sound may be changed as well. They would use the same audio files, but the audio is post-processed using Audio-post-processing logic that is analogous to 3-D Shaders for a graphics card. In both cases lack of such a feature on the sound card would mean the processor deals with it; or, in some cases, you don't get the effect.
As for sound quality, It's more difficult to say. Motherboard Audio could be more susceptible to interference from nearby components on the motherboard if they aren't properly shielded, and sometimes sound cards have their own RF shield to prevent interference with other Adapters or the motherboard. For MP3's or even standard PCM Waveform files I'm not sure if there would be much difference, unless using Post-processing effects or 'improvements' such as "X-Fi Crystalizer" or even sound normalization, both of which can utilize hardware which may improve the quality of that post-processing and will certainly improve performance. Otherwise, it's down to the Signal To Noise Ratio. Most on-board audio has a SnR around 100dB or so; In comparison, X-Fi's using the X-Fi Processor bottom out at around 109dB, while the higher-end models top out at 119dB SnR. The Sonar DG- an inexpensive card, at something like 30 dollars or so, if memory serves- claims around 106dB. The one 'danger' when purchasing a separate audio card is that many are "Value" cards that have a name brand such as X-Fi or the Sonar name, but do not posess any on-card logic and are essentially driven by their driver software. the "SB Live! Value" card doesn't contain a Live! Sound processor, and the Audigy SE doesn't have an Audigy Chip, and the X-Fi XtremeMusic doesn't have a X-Fi Chip either; the features that would normally be provided by such a chip are provided through software emulation. I do not know their particulars in terms of their SnR.
That said, the differences in terms of SnR between such a card and on-board is almost inconsequential. I cannot say that I've perceived any difference between my on-board audio and the Sound card I have.
It really depends on what is being done with it. For games, a dedicated Sound card seems to be the ideal choice- while a game may run amicably today, it could run better- or you could crank sound settings and Hz and so forth- if using a dedicated card. Additionally the off-loading of processing performed by such hardware could become invaluable for games that are released later that 'top out' the system, by offloading processing.