What is the purpose of a separate digital to analog converter?

[playinketchup]

My friend was telling me he needed a digital to analog converter to connect his laptop to a receiver, presumably using a USB port as an output. Without knowing the specifics of his hardware, I was wondering why he couldn't just plug into the RCA jack, isn't that already an analog output? Or is it better to let a dedicated DAC handle the conversion then input to the receiver?

 

[markw]

If one believes that the internal DAC in their gear can be bettered by an external unit then they are free to go for it.

They may or may not be correct, but they will be hard pressed to acknowledge they made a foolish decision once they commit.

 

[agarwalro]

Is it an old receiver or stereo receiver that cannot accept digital signals?

 

[playinketchup]

Sorry I don't know more about it but he connects his ipad to the receiver so my guess is it's new(er). Your comments and questions confirm what I was thinking- the DAC is redundant.

 

[slipperybidness]

The headphone to RCA jacks might sound fine, but it tends to be my last choice at connecting to a computer.

However, it is always worth a try to see if it sounds good before moving up to a sound card or external DAC.

The items that can make the analog out of a computer problematic: Integrated audio on a mobo may not be the greatest, may need to worry about cable shielding on the headphone to RCA, some computers may have inadequate power supply, and inside a computer is a rather EM noisy area.

For these reasons, I prefer a DAC. A decent shielded sound card can also be fine.

Another good option is if the computer has digi coax or optical, then hook that straight to a receiver. Or a cheaper sound card that has one of those outs.

I can tell you from personal experience that a cheapy Dell desktop sounded like crap using the analog outs to stereo stack, but a ~$30 sound card with optical out fixed that.

 

[zhimbo]

What slipperybidness said - analog outs can sometimes sound pretty awful (certainly my old Dell laptop was a problem...hmmm, I'm detecting a theme.)

 

[anamorphic96]

I tend to agree with the above comments as well. A good DAC will cost between 30-150 depending on the functionality your looking for. Anything more than that and your probably wasting your money.

 

[ImcLoud]

I have tried a bunch of dac's, I currently own 3 audioengine d1's {my favorite}, an XDA2 {most I ever paid for a dac $200 but I use it as a preamp and you get a lot for your money with that unit}, a muse usp dac, and a couple fiiO units I have accumulated over time... and if you compare what the 3.5mm output sounds like vs any usb dac you will see the difference, not to mention sometimes the 3.5m rca cables have a noise when plugged into your equipment, I know when I plug my ipad in with the 3.5mm to my hole house system it humms until the material starts, same goes for one of my laptops... But it will play, it just depends on how far you want to go with it...

 

[BoredSysAdmin]

What Mark says in quite sharp way and other in more mannered is pretty much same thing: Plug it in - if you have no background noises, like hum, buzz and others then don't bother.
That said my PC's soundcard (not onboard, rather PCI card from Creative) was making way too much noises to be usable and after some research I decided to pony up and go with optical interfaced dac, same one as ImcLoud has - A.E. D1 - it works quite well and my noises issue is gone....
Now I gather for most folks with pc noise issues, using even a simple a cheap usb dac like Behringer uca202 (using rca line out, NOT 3.5mm port) will most likely fix the issue
it is limited to 48khz/16 bit - not really sufficient for mastering audio, but plenty for playback

 

[highfigh]

The sound card isn't the computer manufacturer's primary focus and they don't put much into this, unless the consumer specifically desires it. OTOH, if they need a great one, it's easier to just buy an outboard piece and select it by specs/sound and other features. The mic in a laptop isn't anything special, either. I was using mine for REW and above 3KHz, almost all response was gone up to about 17KHz which, for some reason, did react to that narrow range. I connected my Tascam UBS-122L and Behringer ECM-8000 and it showed the full range of response. I didn't expect it to be great, but I didn't expect it to be that deficient.