do i need a sound card/dac if im using optical out?

[xunknownx]

hi,
 
i currently have an audigy 2 zs and its been working great for the past 10 years.  i'm currently upgrading my computer and no new motherboards have PCI slots anymore, plus im due for an upgrade anyways.  i really want the asus essence stx II but its not available in the US. and pretty pricey if i really want to get it.  i was doing some reading and i read somewhere that if i want to use optical out, it is just pass through so the sound card plays no part?  is this true?  so if i were to use onboard audio, using the optical port, it would not make a difference if i were to use a nice sound card/dac using the optical output? 
 
i would like to note that i dont play games, i listen mostly to music, 320kb MP3s, and watch anime and movies.  i have logitech z680 thx certified 5.1 speakers.  this is the older generation of the popular z5500. 

 

[SSSN]

1. Indeed, devices connected via optical cables circumvent soundcards almost entirely. Instead, these devices have built-in DACs that convert the digital signal from the optical jack to a analog signal for the loudspeakers.
 
2. Logitech speakers aren't good enough to benefit from a soundcard anyway. Just connect them to your mainboard via optical and be done with it.

 

[PurpleAngel]

   
 
I currently have an Audigy 2 ZS and its been working great for the past 10 years.  I'm currently upgrading my computer and no new motherboards have PCI slots anymore, plus I'm due for an upgrade anyways.  I really want the Asus essence STX II but its not available in the US. and pretty pricey if i really want to get it.  i was doing some reading and i read somewhere that if i want to use optical out, it is just pass through so the sound card plays no part?  is this true?  so if i were to use on-board audio, using the optical port, it would not make a difference if i were to use a nice sound card/dac using the optical output? 
i would like to note that I don't play games, i listen mostly to music, 320kb MP3s, and watch anime and movies.  i have Logitech z680 thx certified 5.1 speakers.  this is the older generation of the popular z5500. 

 
True that using S/PDIF (optical or coaxial) output means the sound card (on-board or add-on) would have zero effect on audio quality (in general) for the speakers.
But you can still use other features on the sound card (on-board or add-on) when using S/PDIF output.
To get 5.1 surround sound when using S/PDIF output, you need to have DDL (Dolby Digital Live) software.
An Asus Xonar DX or D1 sound card (used $60) would come with DDL
 
For watching modern movie disk movies (Blu-ray or DVD) you might consider buying an older version of Cyberlinks PowerDVD, works great for modern movies on disk.
I was able to get PowerDVD 11 Ultra for $30 (eBay), I think it comes with DDL
 
I would not think it's really worth it to get the Asus Essence STX II just for it's analog audio output, for use with the Z680 speakers (at least to me)
Definitely not worth it if your just using the S/PDIF output.
 
For the kind of cash you would spend on the Essence STX II, you might be better off buying the FiiO E10K USB DAC/Amp ($75) and headphones.

 

[cel4145]

I would not think it's really worth it to get the Asus Essence STX II just for it's analog audio output, for use with the Z680 speakers (at least to me)

Agreed.

Instead of the Essense STX II, I would also recommend the Audio-GD NFB-15, which is an external DAC/amp/pre-amp. Has connections for your speakers and multiple inputs. If you want the Dolby Headphone feature of the STX, get the Xonar DG to go with it.

 

[xunknownx]

how would an external DAC help if im just going to use optical?  (not trying to doubt you guys, im just trying to learn and understand)
also how does these dac compare to the audioengine d1? 
 
also note that i will not be using head/ear phones.  i just like to play music in my room while using my desktop

 

[cel4145]

Sorry. I got confused about your needs. I thought you needed a headphone hook up, too. And I didn't realize you have a 5.1 speakers set.

 

[PurpleAngel]

Agreed.

Instead of the Essense STX II, I would also recommend the Audio-GD NFB-15, which is an external DAC/amp/pre-amp. Has connections for your speakers and multiple inputs. If you want the Dolby Headphone feature of the STX, get the Xonar DG to go with it.

 
The NFB-15 is 2-channel (DAC) line-output, the Z680 is a 6-channel (5.1) speaker setup.
But if you know how to get it to work, I'm all ears.