Assuming SPDIF output, what makes one soundcard better than another?

[Eriatarka]

Ive ordered a Zero DAC and I want to connect it to my laptop, but I dont have a SPDIF output so I need to buy some external USB thing to use as a converter. I've done a search on this forum and seen people recommend USB->SPDIF/optical converters that cost about $150. However my local maplin sells a USB soundcard with SPDIF output for $35. Is there any reason why this would be inferior to a more expensive option? Given that I'm only going to be using the soundcard's digital output and bypassing the amp/DAC, are all soundcars pretty much the same? I mean digital is digital, right? Or am I missing something.

[tru\head]

i don't see much justification in spending more than I have to on a generic usb -> spdif connector.

there will always be someone who will argue that various expensive digital components make a difference over cheap generic items (such as using a more expensive optical cable?), but regardless, the price is not justified for a mid-fi setup like zero-dac.

in my opinion, digital signals are digital signals, the only major concern is jitter which I haven't seen any complaints about in the zero-dac thread. many people are using cheap generic usb-spdif connectors with it. digital signals can: work, or, be f'd up. i don't see how it is possible for tonal differences to exist from a different connector or cable transmitting 1's and 0's.

[nor_spoon]

A friend of mine and I connected my Zero DAC to his computer once. We ran digital out from his Asus P5B motherboard and there were constantly small crackling noises. Never heard that using my Echo Mia soundcard, so I guess quality of components/layout do matter.

[mrarroyo]

Originally Posted by nor_spoon

A friend of mine and I connected my Zero DAC to his computer once. We ran digital out from his Asus P5B motherboard and there were constantly small crackling noises. Never heard that using my Echo Mia soundcard, so I guess quality of components/layout do matter.

When you are running a few applications you get the small crackling noises. One way to reduce or eliminate it is by going to task manager and increasing the priority of your music software. It works great on my computer, I do not hear any noises when I up iTunes.

[nor_spoon]

Originally Posted by mrarroyo

When you are running a few applications you get the small crackling noises. One way to reduce or eliminate it is by going to task manager and increasing the priority of your music software. It works great on my computer, I do not hear any noises when I up iTunes.

Yeah, it could be drivers or other things like you say affecting the performance on his computer.
I have not configured my computer for music priority. I guess using a dedicated high quality sound card helps.

[trains are bad]

It doesn't matter. Digital is digital, assuming the interface can at least uphold the spec and not crackle and cut out. That's the whole point of using digital connections, to prevent the sound from being degraded.

[PianistOne111]

They should all be the same. If the signal is bad, the audio doesn't play.

[b0dhi]

So long as the DAC can properly re-clock the digital data it receives, they'd both result in the same quality. From what I gather, there are differences in the quality of re-clocking circuits on DACs, tho.

[jinp6301]

Dont forget that the digital stream should be bit-perfect and not resampled. The TBAAM optical out resamples the data before it gets transmitted so make sure that what you're getting is bitperfect

[regal]

There is one very important feature you need in a SPDIF soundcard : ASIO.

The difference in sound quality with a bitperfect digital output is huge.

I wouldn't buy any thing under a PCI EMU 0404.