Motherboard optical vs dedicated sound card

[R.C.Anderson]

Ok, so I've been wondering this, is there much difference in the audio quality between the optical output from a motherboard, and the analogue output from a decent dedicated sound card?

Theoretically the optical output's quality should depend completely upon the quality of the decoder in the amp, however if this was the case, surely the amp will be pretty much the same quality whether it's an optical, or analogue input to it, and as such, a dedicated sound card would either provide worse quality sound, or the same (as the amp would degrade the quality anyway)

I know none of it works quite as theory says it should, however I don't know how close/far from this it is, or what you need to spend on a sound card in order to get better quality (is it £10, or is it £200?)

If I decide to buy a dedicated card, it will only be a reasonably cheap on (probably £30 or so max), so would I be better off just using the optical out from my motherboard (Asus P8P67 Pro B3 (when it arrives from being replaced )), or should I buy a dedicated card (in which case which?) and use the analogue outputs from that (or even the optical output?)

I hope some of that makes sense to someone, and they can help me with it, it made sense to me whilst I was writing it

 

[Auraomega]

Theoretically the optical output's quality should depend completely upon the quality of the decoder in the amp, however if this was the case, surely the amp will be pretty much the same quality whether it's an optical, or analogue input to it

Not true, the analogue signal will go through the amp no matter it's source, so the amp does play a part, however the difference is with the DAC (digital-analogue converter). The amp converts the digital signal to analogue or the card converts the digital signal to analogue, if you use a cheap and nasty DAC such as the common onboard DACs you'll have poor quality, if you use an external dedicated DAC such as a sound card or an external DAC (be that a DAC Magic or just an AVR) the quality is usually better. However things start to blur here, some people can't tell the difference between DACs, others find them obvious, for example my DG which sounded better than onboard sounds poor compared to my Zero or H/K AVR, however a lot of people can't hear the difference.

I'd say stick with your external DAC as not only is it cheaper it also will have less interference than a sound card in an electrically noisy computer, and the less time the signal is analogue the less likely you are to get noticeable signal degradation.

 

[R.C.Anderson]

Maybe I just didn't eplain what I meant clearly enough, as I know the analogue signal goes through the amp whatever, and therefore the amp plays a part, I'll try to explain what I was meaning more clearly...

For optical output from motherboard:
Raw signal is produced and sent opticaly then, the DAC within amp converts to analogue, and goes through the standard amplification (+any other settings (eg. eq) within the amp), then to the speakers.

For analogue output from dedicated card:
Raw signal is produced, and sent to card digitally, then, the card's DAC converts this, then goes to the amp to the same amplification circuitry that the optical signal would go through once converted within the amp.

What I meant over all, is that both signals would go through the same amplification circuitry, so the only difference is when it gets converted from digital to analogue.

So I think the main thing I was asking is which DACs are better? the ones on a ~£30 sound card, or those within my amp (Sony STR-DB940)? And also, is there any difference between the optical outputs from the motherboard, or from a dedicated card?

 

[AbsenceJam]

So I think the main thing I was asking is which DACs are better? the ones on a ~£30 sound card, or those within my amp (Sony STR-DB940)? And also, is there any difference between the optical outputs from the motherboard, or from a dedicated card?

1) Those on the amp and there's also less EMI to mess with things than there is inside a computer.

2) Nope.

 

[R.C.Anderson]

1) Those on the amp and there's also less EMI to mess with things than there is inside a computer.

2) Nope.

Thanks, that was what I was thinking, but as I'm fairly new to the PC audio situation (or at least beyond using onboard jacks to some cheap speakers), so wanted to make sure