USB vs S/PDIF vs HD Audio Out?

[FMX]

I am curious about the differences between the 3. I did some research and couldn't find a clear answer.

Ok, aside from optical obviously being superior in speed, USB and S/PDIF should technically produce the same sound, since the output is digital, therefore relying on the DAC of the speaker/headphone?

The reason I am curious about all of this is I was considering just getting a cheap pair of headphones since I am by no means an audiophile, but I just want to know what I am getting.

Example: Corsair Vengeance 1500. They connect via USB. Is the sound coming from a raw digital output from the computer and then the Vengeance is converting it to analog, or is the signal already converted by the time it hits the Vengeance? I am confused on how this works.

My Asus P8Z68-V came with an HD audio slot - so did my Fractal Arc Midi in the front port. The Arc is connected to the Asus. Even though this says HD, I assume it is still only stereo and analog? How exactly does this differ in terms of quality between the USB and S/PDIF connections?

 

[plugwash]

USB and S/PDIF should technically produce the same sound, since the output is digital, therefore relying on the DAC of the speaker/headphone?

USB could theoretically be better as S/PDIF is limited to 16 bit 48kHz (unless you get into compressed formats like dolby digital or DTS but those have their own downsides). In practice though I doubt the DACs in a cheap headphone set will support more than 16 bit 48kHz anyway.

My Asus P8Z68-V came with an HD audio slot - so did my Fractal Arc Midi in the front port. The Arc is connected to the Asus. Even though this says HD, I assume it is still only stereo and analog?

It's still analog. It probablly supports multichannel output through some combination of connectors and it may support higher samplerates/bit depths too (that is what intel HDA was designed to support). Whether the analog design is good enough to actually take advantage of higher samplerates and bit depths I do not know.

 

[Forceman]

The S/PDIF and optical connections are purely digital outputs from the game/movie/whatever. The front panel output is an analog output from the DAC on the onboard chip, and will likely be poorer quality than the sound from the S/PDIF or optical, depending on what you have the digital connections hooked up to (like a receiver). The USB headsets basically have a sound card built in, so the sound will be digital from the game, through the headset DAC, and then analog to the actual headset. Whether that is better or worse than the onboard analog depends on the headset you get.

 

[dustNbone]

It will purely come down to the quality of the DAC involved, whereever that may be and however it receives it's digital input is pretty much meaningless.


S/PDIF is the same whether it's carried over optical or coaxial. The bitstreams are exactly the same, just pulses of light in place of pulses of voltage. It's limited to 24 bit 48khz audio in it's basic form, but I'm pretty sure most game audio is at 48khz anyway so that's not really a limitation.

USB is another way to get a digital signal out of the computer and to a DAC, alot more flexible than S/PDIF, allows bidirectional communication between your computer and the audio device, as well as basically unlimited format support, up to the limits of the audio device itself, but as stated above that may only be 24/48 anyway.

Onboard audio just uses the one of the computers internal data buses to transmit digital audio to the DAC intergrated onto the motherboard.

Keep in mind that 24/48 is widely considered the upper edge of human hearing, and there is wide debate over whether there is anything significant to gain with higher sample rates.

Bottom line though, the DAC and its supporting opamps are what produce the analog signal that you ultimately hear, and any of the methods you describe will do a good job getting digital information to the DAC for it to convert. You can sort of tell how good a DAC is by how much it costs. Sorta. Read some reviews.

 

[skeeder]

with Dust...really you need to focus on what you use it for...I do tons of music, so a true 44100hz was more important than an upsampling to 96000.

With Audio--there is never a clear 'winner'.