Loss of sound quality

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Staples

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It seems that a lot of people on this board fully endorse the Xonar (or what ever it is called) sound card even though its high price. They sight its high DAC rating as a justification to buy it. I recently bought a cheap Rocketfish sound card from Best Buy. It has an Audigy chip on it and optical out. I doubt the DAC chip is very good but I bought it for the digital output in which case, the rating of the DAC does not matter at all.

Currently I have the optical output from my card running to a Denon 1910 receiver (which I am sure has decent DAC chips). All this concern with quality of DAC chips on sound cards make me wonder, am I losing quality in the conversion to digital? I think all 5.1 encoding is compressed however I am using 2 channel in which case I think it is transmitted in PCM (which I always thought was lossless RAW data). Am I correct? If so, why is everyone so concerned with onboard DAC quality on their soundcards?
 
Staples said:
It seems that a lot of people on this board fully endorse the Xonar (or what ever it is called) sound card even though its high price. They sight its high DAC rating as a justification to buy it. I recently bought a cheap Rocketfish sound card from Best Buy. It has an Audigy chip on it and optical out. I doubt the DAC chip is very good but I bought it for the digital output in which case, the rating of the DAC does not matter at all.

Currently I have the optical output from my card running to a Denon 1910 receiver (which I am sure has decent DAC chips). All this concern with quality of DAC chips on sound cards make me wonder, am I losing quality in the conversion to digital? I think all 5.1 encoding is compressed however I am using 2 channel in which case I think it is transmitted in PCM (which I always thought was lossless RAW data). Am I correct? If so, why is everyone so concerned with onboard DAC quality on their soundcards?
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yeah, its passing PCM data, although if your source isn't PCM lossless, its simply transcoding your source to meet that, so if you're listening to a 128k mp3, thats being transcoded to PCM spec (just like if you burned that to a CD that a CD player could read), you aren't gaining any quality, you just aren't (in theory) losing anything

and in that case, the card's onboard DAC doesn't matter, as the external D/A is doing the lifting, and there is no real conversion to digital (transcoding is done, but this is unavoidable (This will happen regardless of what output you use, because the D/A's on the soundcard can only accept PCM signals as well)), basically nothing is lost, you're just moving where the processing is done

the reason a lot of people are concerned about the onboard D/A quality, is because a lot of people don't have a fancy external processor or receiver, so if the onboard is crap for driving an analog signal (and usually most of the bitching about "cheap DAC kills the signal" is actually cheap opamps or the card's inability to drive a pair of headphones, but nobody wants to hear about that)

and its "cite"
 
Well here is another question. If I am playing a game and outputting a 5.1 dolby digital signal over the optical, am I losing quality over listening straight from the analog outputs on the sound card (pretend that the DACs of the sound card and the receiver were the same)? I was under the impression that both Dolby Digital and DTS compress the audio signal when it is transfered however is this lossless compression or lossy? My thinking is that if it is lossy, then the quality is degraded when it gets decompressed.
 
ok, I'm really getting sick of these threads with people whining about DDL....

when you're putting 5.1 out via S/PDIF, you either use DDL or DTSC, DDL is 448kbit/s, and DTSC is 1536kbit/s, these would both classify as lossy, and do not matter, here's why:

if you're watching a multi-ch movie, its going to be encoded in DD or DTS, so theres no need for re-encoding (i.e DDL), and if you're doing a multi-ch game, the sound quality is garbage to begin with, so it isn't going to cramp things there (because games generally use compressed audio)

for listening to music, you shouldn't have DDL or DTSC enabled in the first place, just leave it in stereo PCM, and its CD quality (and I'm guessing you're using mp3's, or at best flac, either way, 1411kbit/s is more than enough bandwidth)

in other words, there is no downside to DDL/DTSC, unless you don't have a digital processor/decoder to handle the signal
 
Thanks for answering my question and my follow up question. I learned quite a bit in this thread.

But one last question. Just about everything supports DD output/input but do these Xonar sound cards support DTS output? Furthermore, do many PC speakers even decode DTS?
 
Well I care about the DAC's and having a decent sound card because the card is directly connected to my amplifer via three analogue 3.5mm to 2xRCA cables for 5.1 high definition (i.e. for BluRay movies) sound. With no fancy receiver, the sound card does everything, so it had better be decent. And the Xonar is actually not very expensive if you look around - I certainly paid less for my setup than most people who went the receiver route.
 
Staples said:
Thanks for answering my question and my follow up question. I learned quite a bit in this thread.

But one last question. Just about everything supports DD output/input but do these Xonar sound cards support DTS output? Furthermore, do many PC speakers even decode DTS?
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I'm not sure, I know HDAV should do DTS-MA, I'm guessing it should do DTS:C though (at least under Vista/7)

as far as PC speakers and DTS, I only know of one set that does DD (Logitech), but basically any modern receiver will do DTS decoding, and generally this is the application I'd use DTS:C for
 
Staples said:
My thinking is that if it is lossy, then the quality is degraded when it gets decompressed.
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There is degradation during the encoding (compression) stage, but not during the decoding (decompression) stage. Technically speaking, lossy decoding is a lossless process.
 
It's better to be informed and confused than it is to be uninformed and content, I think ;)
 
Please allow me to noob up this thread further with my noob question.

I have music files (FLAC, MP3).

I am buying a SFF/laptop. The computer I'm buying has an S/PDIF out (either on the mobo or on the soundcard).

I want the sound to come out of my receiver (which is powering my speakers or my headphones).

My common sense is telling me the best way to do this is to just use S/PDIF out from the computer to S/PDIF in on my receiver.

Is this hindering sound quality in anyway using this method? Am I effectively eliminating the soundcard (whether on board or using a discrete solution) from the equation so everything is done by the receiver? This is what I am hoping for, the computer just sends it out untouched, and the receiver does the rest.

What do you guys think? Noob enough for you?
 
CJRP said:
My common sense is telling me the best way to do this is to just use S/PDIF out from the computer to S/PDIF in on my receiver.
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Most likely, yes.

CJRP said:
Is this hindering sound quality in anyway using this method?
Click to expand...
Technically, no. You're simply relying on S/PDIF as a transport mechanism.

CJRP said:
Am I effectively eliminating the soundcard (whether on board or using a discrete solution) from the equation so everything is done by the receiver?
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Yes.

CJRP said:
Noob enough for you?
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I've seen worse.
 
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