Questions about external DAC

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supapuffy

Weaksauce
Joined
Jan 6, 2008
Messages
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hi,

first i want to thank everyone on the forums on the useful info about computer audio and speakers/headphones!! ;)

i've got a set of swan m10's and koss sb40 headphones on the way.. connecting to onboard audio chip (ADI® AD1988B on Asus P5K-E) until my next minor upgrade.. these will be used for light gaming (team fortress 2), watching tv and listening to music.. and will be used until the next major upgrade to a setup of receiver + monitors + sub once i have more space/funds to set everything up

i'm considering a zero dac for my next minor upgrade to drive the headphones.. and i have a few questions about the zero DAC (and other external DAC's in general)

1. external DAC's are sometimes referred to as "USB" DAC's.. does that mean a USB to S/PDIF connection from PC to DAC is preferred over using the S/PDIF out of the onboard audio chip?

2. can i use the pre-amp output of the zero DAC to drive the internally amplified swan m10's? this way i can use the pre-amp button to switch outputs without unplugging speakers/headphones?

3. do i need to worry about the different dolby encodings that needs to be done by the PC for an external DAC + headphones setup?

4. i also have a xbox 360, would it benefit from having a zero DAC? i prefer console gaming with speakers.. so this may not apply if the answer for question #2 was a no.. and i'll have to wait until my next major upgrade (receiver) to hook up the 360

thanks in advance!
 
  1. A USB DAC gets its digital signal over a USB connection. No S/PDIF involved. No onboard audio or sound card involved at all, ever again - at most, you just have to change your computer's default audio device.
  2. Yes.
  3. For the most part, you can ignore Dolby - it's intended as a surround encapsulation format. You're not encapsulating or decoding any surround sound signals, so it's not an issue. Save this for when you go to buy a receiver - THEN it will be worth looking at.
  4. That depends on the source quality, but I'm doubtful that game consoles do sound-over-USB. Not that they couldn't, I've just never heard of someone doing this. BUT, the Zero has "One independent digital fiber input; One independent digital coaxial input" - which would be perfectly appropriate to use with your Xbox or other non-computer source.
 
thanks for the quick response!

1. referring to the Zero DAC in particular.. since it doesn't have a USB port for input.. i guess the options to use it with a PC are

* USB --> optical out convertor cable
* simply an optical cable from onboard sound digital out to the DAC

i understand that digital is digital so cables will not affect the quality of the data.. but i was not sure if the optical out of the onboard sound chip has some processing done by the hardware and/or drivers before it's streamed out.. whereas a USB --> optical cable would bypass the onboard sound hardware/drivers and be directly from the source (games/media player software)

edit: meant to say in the USB --> optical cable connection case:
hm.. i guess this depends on what kind of device windows treats the external DAC as.. and how the DirectSound3D API works with the driver?
 
Even if the onboard card does carry out any processing before using the digital outputs - it's entirely in the digital domain, no different from the CPU decoding a FLAC file or a game specifying a number of sources for footsteps.

You're right though, it doesn't look like it takes USB, so you'll need some sort of digital out. I wish the guy that wrote up that article had taken some shots of the back and not just the front and guts. :p


Windows doesn't treat an external DAC as anything if it's connected over coax/optical. No USB = Windows can't see it. The computer sends the signal and needs drivers for the sound card, but it largely acts as a transmitter.
 
02-1.jpg
 
thx for posting the pic!

that's the same shot of the back side of the Zero DAC that caused me to wonder about the "USB" part of the connection from PC to DAC

i forgot to mention that i also have a macbook pro.. which has a mini toslink optical out port.. so i guess the same question applies

To Zero DAC owners,

5. does it come with a USB --> S/PDIF or coaxial cable?

6. have you noticed a quality difference between connecting via USB vs onboard audio optical out?

thanks!
 
There's no such thing as a USB to SPDIF cable. You would need some sort of electronics in the middle since they are different transmission standards. It was my mistake as I've already said; just use the digital out on your motherboard.

Digital is digital is digital. Digital over USB sounds exactly like digital over coax sounds exactly like digital over optical sounds exactly like digital over a network of trained squirrels. It's the analog electronics that matter - the DAC and forward.
 
that makes sense and it simplify things as i just need to connect it to the onboard audio's optical out

i saw some ebay listings selling the Zero DAC also offering "Xitel MD-Port DG2, USB Optical Fibre Sound Blaster":

d5ef_1_sbl.JPG


i guess that's the device that lets you go from USB to S/PDIF if you didn't have an onboard audio chip to start with

now i guess it's time to hunt for a deal on the Zero DAC!

thanks for the help!
 
If your description is accurate, yes.

It's a relatively simple piece of electronics since the whole mess is still in the digital domain - there is just a difference in how the signal is transmitted. But it does require an actual chip, not just a cable (although you could presumably build the electronics inline and make a "cable" that does it).
 
you should be fine using the mac's optical output to the dac. i've listened to a few macs via digital out and i doubt that, this plastic box will provide a better digital signal than the mac.

i own the zero myself and i can tell you that you wont be disappointed, it's a great little unit for the money.
 
I Own the Zero and use it for both PC and Xbox 360.

For the 360 use the Optical out to the Zero. Make sure that you use Digital Stereo output in the Xbox settings. The Zero cant decose 5.1 audio, it gets confused and all static trying to decode 5 channels into two.

For the PC use the Coax SPDIF output on the back of your motherboard. you dont need a USB adaptor yout MB had Digital out. There is a Pic below it is labeled #2. This will allow you to use both without a cable swap.

Damn Picture wouldnt show up but its in you manual on page 2-23.
 
^^ while this would work theoretical, it doesn't work for the op.
he said that his mac book has optical digital out and since the xbox has optical output as well, he need either a optical to coaxial converter for one device or a optical switch box.
 
shadowlord said:
^^ while this would work theoretical, it doesn't work for the op.
he said that his mac book has optical digital out and since the xbox has optical output as well, he need either a optical to coaxial converter for one device or a optical switch box.
Click to expand...

OP was the P5K-E MB and the Xbox 360. The Macbook was mentioned in one of the Replies and I missed it.;)
 
oops, i somehow managed to forget the p5k-e when i reached the post with the macbook. ;)

to sum it up: using p5k-e and xbox would work, but macbook and xbox or even p5k-e, macbook and xbox would require a switch.
 
shadowlord said:
^^ while this would work theoretical, it doesn't work for the op.
he said that his mac book has optical digital out and since the xbox has optical output as well, he need either a optical to coaxial converter for one device or a optical switch box.
Click to expand...

the op can probably use this.. I used to use it to convert coax/optical but noticed it is bidirectional too.

co2.jpg
 
thx for the advices!

my main use will be for the pc connected via onboard audio s/pdif or coaxial out.. with headphones and the pre-amp going out to my swan m10's

the macbook pro and xbox360 will be occasional use so i dont' mind unplugging cables for that.. i brought up the macbook pro because i don't have any speakers that take an optical in.. so i wanted to the dac to be as flexible as possible.. and i think the zero dac seems to work out for all my sources
 
Well now remember, a receiver is a dac too. You get at least 3 digital inputs.
 
yeah but i dont have the space to put all the systems in 1 room right now so i want something a bit smaller/portable for now to get a taste of using a dac first..

i think once i move to new apartment/condo and have the space for all the systems together i'll want to invest in a separate system of receivers/speakers/sub

thx
 
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