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post #1 of 54 Old 05-23-2012, 05:18 AM - Thread Starter
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I listen to FLAC files that come from my PC. My DAC accepts both USB and SPDIF.

Should I use USB or SPDIF to send the digital content?

Is content sent via TOSLINK/SPDIF processed at all?

Are either formats lossy?

Which is superior in the audiophile universe?

Merci!
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post #2 of 54 Old 05-23-2012, 05:43 AM
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Quote:
Originally Posted by michaelkingdom View Post

I listen to FLAC files that come from my PC. My DAC accepts both USB and SPDIF.

Should I use USB or SPDIF to send the digital content?

Is content sent via TOSLINK/SPDIF processed at all?

Are either formats lossy?

Which is superior in the audiophile universe?

Merci!

Do like I did. Try both on your system. If like me- they both sound great, but I listen more to usb because I read it is better. FLACK/WAV/AIFF are lossless.
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post #3 of 54 Old 05-23-2012, 06:14 AM
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Quote:
Originally Posted by michaelkingdom View Post

I listen to FLAC files that come from my PC. My DAC accepts both USB and SPDIF.

Should I use USB or SPDIF to send the digital content?

Depending on the circumstance, they may work equally well. Both have the potential to be sonically transparent, that is have no audible effect on sound quality. Either can possibly be sonically perfect and ideal.

Quote:


Is content sent via TOSLINK/SPDIF processed at all?

No.

Quote:


Are either formats lossy?

No.

Quote:


Which is superior in the audiophile universe?

Depends which audiophile you talk to. ;-)

I would suspect that there might be an audiophile preference for SP/DIF, but this information may be meaningless in your particular situation. Both alternatives can work well.

A SP/DIF signal generated inside a PC generally has less overhead than USB, but YMMV.
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post #4 of 54 Old 05-23-2012, 06:30 AM
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Quote:
Originally Posted by michaelkingdom View Post

I listen to FLAC files that come from my PC. My DAC accepts both USB and SPDIF.

Should I use USB or SPDIF to send the digital content?

Is content sent via TOSLINK/SPDIF processed at all?

Are either formats lossy?

Which is superior in the audiophile universe?

Merci!

Depending on the brand/model DAC you have and the bitrate of the files you want to play. My DAC supports 16/44.1kHz to 24/192kHz (Coax, AES/EBU, Toslink) and only up to 24/48kHz (USB). Since I only play 16/44 music files, I use USB because I feel I get much solid connection to my MacMini regardless of the lower bitrate support of the USB connection compared to the optical.
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post #5 of 54 Old 05-23-2012, 07:01 AM - Thread Starter
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Well, I have been going back and forth between them.

I have level matched the volumes and turned off all internal processing in the computer.

USB sounds crisper - the high crash of a cymbal sounds brighter and more separate. Voices do not bleed together with bass notes. Placement on the stage is more distinct.

S/PDIF has a fuller sound. Everything sounds warmer and less defined. Voices lack the brilliant stand-alone quality in USB. I can add a little bit more treble through processing or manual treble controls but the soundstage is still less dynamic.

The differences are not huge but USB is definitely more analytical.

I searched to see if I am doing something wrong but I have disabled any soundcard software. It's just pure digital to the same DAC via USB ans S/PDIF.
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post #6 of 54 Old 05-23-2012, 07:20 AM
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Quote:
Originally Posted by michaelkingdom View Post

Well, I have been going back and forth between them.

I have level matched the volumes and turned off all internal processing in the computer.

USB sounds crisper - the high crash of a cymbal sounds brighter and more separate. Voices do not bleed together with bass notes. Placement on the stage is more distinct.

S/PDIF has a fuller sound. Everything sounds warmer and less defined. Voices lack the brilliant stand-alone quality in USB. I can add a little bit more treble through processing or manual treble controls but the soundstage is still less dynamic.

The differences are not huge but USB is definitely more analytical.

I searched to see if I am doing something wrong but I have disabled any soundcard software. It's just pure digital to the same DAC via USB ans S/PDIF.


Unfortunately, not a level-matched, time-synched, blind evaluation. Level matching is probable, but not assured. The rest are critical.

But, if you like the USB, go for it!
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post #7 of 54 Old 05-23-2012, 11:08 AM
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post #8 of 54 Old 05-23-2012, 06:05 PM - Thread Starter
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Regarding level matched, time synced and blind, I did come pretty close.

I play the files from my computer with USB and S/PDIF both connected. I will switch back and forth quickly on the same song I am very familiar with. When volume is at the same level I was switching back and forth so many times that I forgot what day it was.

USB and S/PDIF sound fundamentally different. I just wish I understood why and if I am screwing up the S/PDIF somehow.
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post #9 of 54 Old 05-24-2012, 04:41 AM
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Originally Posted by michaelkingdom View Post

Regarding level matched, time synced and blind, I did come pretty close.

I play the files from my computer with USB and S/PDIF both connected. I will switch back and forth quickly on the same song I am very familiar with. When volume is at the same level I was switching back and forth so many times that I forgot what day it was.

USB and S/PDIF sound fundamentally different. I just wish I understood why and if I am screwing up the S/PDIF somehow.

Not double blind is like missing doing it right by a country mile. You're right about one thing, and that is if they actually sound different, at least one of them is pretty badly screwed up.
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post #10 of 54 Old 05-24-2012, 08:26 AM - Thread Starter
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I wonder if the sonic differences indicate a set up error or if the sound characteristics are inherent to the delivery method. ...
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post #11 of 54 Old 05-24-2012, 08:47 AM
 
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My thought would be the physical characteristics, not the logical characteristics.

They both are untouched digital signals, but a dirty port, a fingerprint on the copper or optical, some dust in either end of the optical ports, the fact that light is not manipulated as easily from outside sources (magnetic fields and other waves), a really really nice SP/DIF cable and a used, bent, old USB cable, etc. etc.

Rarely in life can anything be measured exactly with even properties. The fact is both mediums carry the exact same digital signal, so this question is more about what kind of medium you have and how good it sounds to you.

I could probably make a case for either one being better in a given situation due to the fact that either medium could in that particular case be better than the other.
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post #12 of 54 Old 05-24-2012, 09:10 AM
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Originally Posted by michaelkingdom View Post

I wonder if the sonic differences...

...which are yet to have been ascertained by any reliable means.

If an audible difference is there, then it is measurable. There may be some means to loop back the signal and measure it using the Audio Rightmark freeware analysis software.
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post #13 of 54 Old 05-28-2012, 02:16 AM
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Quote:
Originally Posted by michaelkingdom View Post

Is content sent via TOSLINK/SPDIF processed at all?

Are you achieving bit-perfect output with your PC and media player when using SPDIF? i.e. does the volume control on the media player or the main one on the PC's desktop still work..?

If they do, then your OS is doing some processing on the audio stream. That would explain the audible difference between SPDIF and USB.
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post #14 of 54 Old 05-28-2012, 07:12 PM - Thread Starter
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The volume control works via SPDIF and USB. I have done a lot of A/Bing over the last week. My observations of the different characteristics have not changed but something interesting has happened - certain music that I did not like via USB sounds great via SPDIF.

SPDIF is less bright. Everything is still there but it is blended better. Rock and electronic based music sounds great. SPDIF seems to have a more cohesive bottom end (below 150 hZ) Conversely, in 2 channel, Adele and Diana Krall are way better via USB. Their separation from the other instruments is wonderful.
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post #15 of 54 Old 05-30-2012, 08:20 PM
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Quote:
Originally Posted by michaelkingdom View Post

The volume control works via SPDIF and USB. I have done a lot of A/Bing over the last week. My observations of the different characteristics have not changed but something interesting has happened - certain music that I did not like via USB sounds great via SPDIF.

SPDIF is less bright. Everything is still there but it is blended better. Rock and electronic based music sounds great. SPDIF seems to have a more cohesive bottom end (below 150 hZ) Conversely, in 2 channel, Adele and Diana Krall are way better via USB. Their separation from the other instruments is wonderful.

My own experience is that digital coax cable > ordinary USB cable (I think asynchronous USB is the newer one, but still not that common and still very expensive (but I could be wrong about "expensive" )) > digital optical cable (aka Toslink).

Look up the terms S/PDIF and USB and Toslink on wikipedia.org for a much more complete set of info and refs. Toslink is very limited on max cable length (again see the wiki writeup).

There's also a recent/short AVS thread on "Coaxial Audio: Special Cable?" at http://www.avsforum.com/avs-vb/showthread.php?t=1412447

My own personal preference for RCA interconnect cables (either analog or digital) is the reasonable http://www.bluejeancable.com/store/d...udio/index.htm

I see zero reason to spend more for an interconnect cable than the above no matter how into high end audio you are.

BJC prefers the Belden 1694A due to it being rated for in wall use, and offer it in many colors. The Belden is an excellent cable; my own slight preference is the competing Canare cable, but BJC only offers that in black. I placed an order yesterday for 7 of these cables (6 for 5.1 analog, and one for digital) and didn't have a qualm on using their Belden 1694A; I went with 7' for the one that I'll use for S/PDIF digital data transmission even though I only need 2 or 3 foot. Read the ref that both amirm and I provided in the above AVS ref for technical reasons why minimum length is important for a digital coax cable.

I responded to you due to you having actually done some repeat posting.

Good luck with whatever choice you go with.

The best is the enemy of the good. Voltaire (1694-1778)

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post #16 of 54 Old 06-07-2012, 09:30 AM
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What Ysay said...it depends on your DAC and its limitations. The last couple of DACs I looked into clearly stated that SPDIF offered superior res, with Toslink & USB coming in second.
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post #17 of 54 Old 06-08-2012, 06:04 AM
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Originally Posted by JohnyBGood View Post

What Ysay said...it depends on your DAC and its limitations. The last couple of DACs I looked into clearly stated that SPDIF offered superior res, with Toslink & USB coming in second.

The irony being that in all three cases, the little DAC chip inside the product saw the identical same bits.

A well made DAC works that way, so the exceptions that you mention were obviously inferior designs. Please list them so that we can all avoid them.
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post #18 of 54 Old 06-08-2012, 06:08 AM
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Originally Posted by OtherSongs View Post


My own experience is that digital coax cable > ordinary USB cable (I think asynchronous USB is the newer one, but still not that common and still very expensive (but I could be wrong about "expensive"
)) > digital optical cable (aka Toslink).


Look up the terms S/PDIF and USB and Toslink on wikipedia.org for a much more complete set of info and refs. Toslink is very limited on max cable length (again see the wiki writeup).

Calling the usual 10 meter length limit for TOSLINK "very limited" seems to be a stretch. BTW, this limit can be finessed several ways for not a lot of dough or any performance loss.

Quote:
There's also a recent/short AVS thread on "Coaxial Audio: Special Cable?" at http://www.avsforum.com/avs-vb/showthread.php?t=1412447

The only reasonable summary being that a good comodity cable with a nominal cost is all that is needed.
Quote:
My own personal preference for RCA interconnect cables (either analog or digital) is the reasonable http://www.bluejeancable.com/store/d...udio/index.htm


I see zero reason to spend more for an interconnect cable than the above no matter how into high end audio you are.

Agreed.

Quote:
BJC prefers the Belden 1694A due to it being rated for in wall use, and offer it in many colors. The Belden is an excellent cable; my own slight preference is the competing Canare cable, but BJC only offers that in black. I placed an order yesterday for 7 of these cables (6 for 5.1 analog, and one for digital) and didn't have a qualm on using their Belden 1694A; I went with 7' for the one that I'll use for S/PDIF digital data transmission even though I only need 2 or 3 foot. Read the ref that both amirm and I provided in the above AVS ref for technical reasons why minimum length is important for a digital coax cable.

I've used 1694A, and its wonderful stuff - way into overkill for most uses, and still reasonably priced.
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post #19 of 54 Old 06-08-2012, 06:13 AM
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Quote:
Originally Posted by michaelkingdom View Post

The volume control works via SPDIF and USB. I have done a lot of A/Bing over the last week. My observations of the different characteristics have not changed but something interesting has happened - certain music that I did not like via USB sounds great via SPDIF.


SPDIF is less bright. Everything is still there but it is blended better. Rock and electronic based music sounds great. SPDIF seems to have a more cohesive bottom end (below 150 hZ) Conversely, in 2 channel, Adele and Diana Krall are way better via USB. Their separation from the other instruments is wonderful.

And that is why so many of us find sighted evaluations to be so frustrating.
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post #20 of 54 Old 06-16-2012, 04:20 PM
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there's no black or white reply possible here.....it depends on what chips are being used in your DAC and your transport smile.gif

the best S/PDIF receiver is WM8804 because it reclocks internally to 50ps, and the best USB controller is the XMOS chipset because it runs two low jitter clocks that are multiples of 44.1 and 48khz and it doesn't require any driver for any other OS than windows.

If your DAC has PCM2704 and CS8416, then they're both worthless tongue.gif
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post #21 of 54 Old 06-17-2012, 07:22 AM
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Originally Posted by leeperry View Post

there's no black or white reply possible here.....it depends on what chips are being used in your DAC and your transport smile.gif
the best S/PDIF receiver is WM8804 because it reclocks internally to 50ps, and the best USB controller is the XMOS chipset because it runs two low jitter clocks that are multiples of 44.1 and 48khz and it doesn't require any driver for any other OS than windows.
If your DAC has PCM2704 and CS8416, then they're both worthless tongue.gif

This is the correct answer. USB has the lowest potential jitter rate amongst any PC transport mechanism when it is asynchronous Class 2 audio. For any SPDIF and USB implementation it really depends on the chip you are using. The most popular SPDIF chips are the DIR9001 and the WM8804. The DIR9001 to some people sounds better, but it is limited to 24/96. The WM8804 can do up to 24/192 but most say that it doesn't sound as good as the DIR9001. Both chips are spec'd to provide less than 50ps of jitter. Asynchronous USB jitter has been measured at < 5ps.
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Originally Posted by Greg121986 View Post

to some people sounds better, but it is limited to 24/96.
What kind of process did they use to find that out?
Quote:
The WM8804 can do up to 24/192 but most say that it doesn't sound as good as the DIR9001.
Again, what kind of process did they use to find that out?
Quote:
Both chips are spec'd to provide less than 50ps of jitter. Asynchronous USB jitter has been measured at < 5ps.
So what's the benefit?
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post #23 of 54 Old 06-17-2012, 08:24 AM
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What kind of process did they use to find that out?
Again, what kind of process did they use to find that out?
So what's the benefit?

Maybe they used some kind of scientific double-blind wizardry?

What would you have done, Wise Professor of Precision Audio Measurements? rolleyes.gifrolleyes.gif
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post #24 of 54 Old 06-17-2012, 08:39 AM
 
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Originally Posted by Greg121986 View Post

Maybe they used some kind of scientific double-blind wizardry?
Maybe? In other words, you don't know.
Quote:
What would you have done, Wise Professor of Precision Audio Measurements? rolleyes.gifrolleyes.gif
Too bad you had to resort to name calling. What I would do it to find out how some people come up with the results that contradict the existing results coming from objective comparison methods instead of blindly following like you do.
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post #25 of 54 Old 06-17-2012, 09:48 AM
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Originally Posted by Greg121986 View Post

This is the correct answer. USB has the lowest potential jitter rate amongst any PC transport mechanism when it is asynchronous Class 2 audio. For any SPDIF and USB implementation it really depends on the chip you are using. The most popular SPDIF chips are the DIR9001 and the WM8804. The DIR9001 to some people sounds better, but it is limited to 24/96. The WM8804 can do up to 24/192 but most say that it doesn't sound as good as the DIR9001. Both chips are spec'd to provide less than 50ps of jitter. Asynchronous USB jitter has been measured at < 5ps.

 

Thanks, well I've gone through a hell lot of trial and error before making up my mind ^^

 

The biggest issue with WM8804 is that most companies enslave it to a low resolution clock and their customers expect miracles duh....the "Firestone Bravo" uses a 0ppm clock conditioner from TI, and I can tell you that WM8804 gives the good when it comes to reclocking if it's driven off a nearly perfect clock and linear regulated PSU cool.gif

 

CS8416 is still widely used because DIR9001 is indeed limited to 24/96 and WM8804 doesn't do AES/EBU at all.......the major issue is that CS8416 in "high jitter" 192kHz legacy mode exhibits +500ps of jitter at 44.1kHz, duh again: http://www.cirrus.com/en/pubs/appNote/AN339REV1.pdf

 

Don't mix the 50ps clock recovery of DIR9001 w/ the 50ps reclocking of WM8804, these are two completely different mechanisms...you can check out the AES white papers on Wolfson's site.

 

It's easy to understand why most companies give up on S/PDIF these days, because it's a terribly obsolete protocol due to its embedded slaved clock that has to be extracted: http://www.gearslutz.com/board/1788545-post2.html

 

Quote:
S/PDIF is a horrendously poorly designed interface. This is because it combines the clock and audio coding onto the same signal. The receiver is supposed to recover the clock from this signal as well as extract the audio data. This turns out to be a non-trivial task, and one that almost always leaves the recovered clock contaminated with signal correlated jitter artefacts.

 

XMOS USB and I2S is all you need, give up on S/PDIF and you'll be just fine biggrin.gif

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post #26 of 54 Old 06-17-2012, 03:01 PM
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Originally Posted by leeperry View Post

It's easy to understand why most companies give up on S/PDIF these days, because it's a terribly obsolete protocol due to its embedded slaved clock that has to be extracted: http://www.gearslutz.com/board/1788545-post2.html


XMOS USB and I2S is all you need, give up on S/PDIF and you'll be just fine biggrin.gif

What's minimum cost for a desktop PC (OS=Windows7) with asynchronous USB output?

I mean does it even exist?

Kindly name one minimum cost external stand alone DAC with asynchronous USB input. Thanks.

And why exactly is that likely to sound better than a modest current PC mobo with S\PDIF output via coax RCA cable?

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post #27 of 54 Old 06-17-2012, 04:07 PM
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Originally Posted by OtherSongs View Post

What's minimum cost for a desktop PC (OS=Windows7) with asynchronous USB output?
I mean does it even exist?
Kindly name one minimum cost external stand alone DAC with asynchronous USB input. Thanks.
And why exactly is that likely to sound better than a modest current PC mobo with S\PDIF output via coax RCA cable?

The iBasso D7 is one of the cheaper XMOS based DACs that I have come across. It has a decent headphone amp, and it can be used with its line-out function for when you want to use an external headphone amp or run it into a preamp. It is pretty good for the features it offers and its price.
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post #28 of 54 Old 06-18-2012, 11:16 AM
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Originally Posted by Greg121986 View Post

The iBasso D7 is one of the cheaper XMOS based DACs that I have come across. It has a decent headphone amp, and it can be used with its line-out function for when you want to use an external headphone amp or run it into a preamp. It is pretty good for the features it offers and its price.

But then, doesn't one also need a source that provides digital stereo files (even just 16/44.1) over asynchronous USB as output? FWIW I'm not sure of the prior wording, but the suspect the essence is correct. Meaning that to be "asynchronous USB" *both* the source and DAC must have asynchronous USB capability.

The only blu-ray player that I know of that has asynchronous USB, for CD playback, is the very expensive Ayre DX-5 blu-ray player. And of course Ayre also has a very expensive DAC that only does USB connection including asynchronous.

My own impression of the whole asynchronous USB connection thing is that few people really do it for real.

It also remains unclear to me if asynchronous USB is offered on PC/Windows computers.

So I was more than a little surprised to find "asynchronous" mentioned with lower cost DACs like your above mentioned iBasso D7!

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post #29 of 54 Old 06-18-2012, 12:39 PM
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Asynchronous USB requires a driver for use with Windows. There are a few different chips that I know of that will do 24/192 Asynchronous. The XMOS, the Tenor TE8802, and the CMedia CM6631. Each of these chips requires a different driver so you'll want to look to the manufacturer to give you a link to the correct download for the driver. IBasso has their driver on their website. If you are on a MAC, the chips should work without a driver.

As far as I know, Ayre uses the XMOS chip as well. I have not listened to the Ayre DAC yet but I have heard good things about it. USB Audio is not quite "mainstream" yet. You will find many manufacturers commenting about how difficult it is to provide a good USB solution on their DACs. Many were working with 24/48 limitations of some of the older USB designs, and some were using 24/96 which is a limitation of USB Class 1. However, USB Class 1 can work with Windows native sound drivers which means you shouldn't have to install a secondary driver.

I'm not sure how IBasso obtained the XMOS chip for such a low price. Each manufacturer that uses the XMOS has to pay a royalty to the designers of the XMOS chip. I know a reference XMOS Development board costs $150, so the XMOS design is certainly not cheap. You can read some more about it here.
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post #30 of 54 Old 06-18-2012, 02:26 PM
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Hi Greg,

Thanks for the insight. Very informative.
Quote:
Originally Posted by Greg121986 View Post

. . . I know a reference XMOS Development board costs $150, so the XMOS design is certainly not cheap. . .
I don't think you can extrapolate the cost of the part based on the cost of the development board. I've spent up to $500 for development boards that contained no more than $40 in parts-cost. The cost of any particular development board is more geared to 1) offset the cost of support that the developer may need, 2) offset the cost of manufacturing, which can be high with such a small production run, and 3) keep the hobbyists away.

I can understand audio manufacturers having issues implementing a protocol such as USB. I have found with the USB devices that I have designed (none for audio) that just the negotiation to get your device recognized by the OS is a challenge, no matter how simple your device is. When you then add the requirement to provide your own USB driver, you are far afield of what an audio engineer is used to.

I suspect that the pain-factor associated with asynchronous USB will be short-lived, and as more implementations are released, the price will dwindle back down to where isochronous USB is (in other words, no added premium for asynchronous USB). It's just a matter of time, and I'm hoping not much.
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