Is sound card redundant?
Because now every mobo comes with quite good built-in sound chip.
Even up to 7.1

I think sound card business is dead!

There are still professional soundcards, either the ones for gamers with EAX (hardware based surround sound) or for music professionals with very high quality and a whole bunch of input/output possibilities. Other than that, nowadays onboard sound is pretty good and if you aren't extremely audiophil you won't need an extra soundcard.

Kind of like saying the video card business is dead.

Video card was dead, long time ago when my PC was 386 system,
I did buy Diamond video card to watch VCD.

Comparing an AV Receiver with the best Sound Card, which one can produce the best quality of sound?

There are 5.1 or 7.1 PC speaker system,
I wonder how do you position those speakers so that you can hear the "surround" effect?
It is very inconvenient to place so many speakers.
If you put all in front of you, there is no more "surround".

@future_computer: This far from the first thread you have started which is simply fishing for the opinions of those more knowledgeable and playing 'Devil's Advocate' with them endlessly plying them with more questions if they answer you. Do you learn anything from them? What's your goal? What prevents you reading up and forming your own opinions?

I'd think that a dedicated sound system would outperform a sound card. A nice McIntosh system would suit me.

A good sound card is cleaner and clearer than onboard sound. How much you will notice the difference between onboard sound and a good sound card will depend on what you are playing, how good your amp/speakers are, and how good your ear is.

'Best' sound card? Doesnt exist.

Some AV/receivers have very good quailty sound, some of them are pure junk.

In some situations, the sound acrd will not matter at all (e.g. if you are bitstreaming the audio from DVD/blu ray via digital output, S/PDIF or HMDI). In those cases the sound card just passes the signal and doesnt do any decoding at all, its all done in by the receiver etc..

Apple mostly uses onboard sound, and its the same chips that are in windows systems. Apples wont sound any better than a normal windows computer.

With the extra cost of an apple system over a normal computer, you could afford to get a nice sound card.

I used to use a separate soundcard because it was less noisy than the onboard and had RCI jacks on it and I use a pair of active monitors. I still had to use a transformer to stop ground hum though. Now I just use the onboard soundcard outputting through and optical cable to a cheap DAC -- ground loop problem solved .
A friend, however, still uses a soundcard because he uses digital in and out as well as the stereo RCA jacks for his many instruments.
As mentioned above, different uses need different solutions, as they do in the graphics card side of things also.

I am talking about AV receiver like Yamaha, Onkyo.