# 24bit/196Khz in car?



## blueteq (Jul 19, 2011)

Hi new here, and frankly new to car audio. For years I have been a dedicated audiophile in my home. Never in my car, and the fact that my wife is not into loud music I want to start enjoying my ,USC in the car.

I have a Linn DS streaming my digital library of studio master tracks which I have been collecting for a while now. All in FLAC or WAV format, and just over a TB in size. 

Now I know that your car is not the best environment for critical music listening, but I a, not an audiophile at that level and enjoy good quality music more. My current Eclipse AVN-726E has the iPod dock connector through which I play some of my FLAC content using the IOS FLAC player, and it sound much better than my iTunes tracks. Even if the iPhone only puts out 16bit/44Khz.
So I got thinking that if you get a good head unit that have a 24bit/192khz DAC it will sound even better. But I cannot find anything. 
Best solution so far is the Clarion unit with optical in, sending the FLAC files using a car computer over a SPDIF connection. 
Has anyone looked at something like this?Or does car audio just work differently?


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## blueteq (Jul 19, 2011)

Was this asked in the wrong thread? Or was the question not appropriate ?

I would really appreciate some help....


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I am here: http://maps.google.com/maps?ll=-37.814892,145.202214


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## ReticulatingPigeonElf (Sep 22, 2010)

blueteq said:


> So I got thinking that if you get a good head unit that have a 24bit/192khz DAC it will sound even better. But I cannot find anything.


I think this is trend largely set by the music industry itself and will only evolve when artists/record companies start employing something other than redbook compression as a standard. And considering the lack of adaptation of DVD-A/SACD, as well as the floundering business of recorded music itself, I wouldn't expect things to change drastically anytime soon.


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## blueteq (Jul 19, 2011)

I agree which is part of my frustration, for the last two years I have owned a high def digital
Streaming player at home. My HD Audio collection is well over a TB now. Access to online stores which provide HD content could improve, my main sources are linnrecords.co.uk, hdtracks.com and B&W society of sound. 
You would hope artist jump on HD wagon, like Nine Inch Nails and Radiohead did.

I do find car audio not to have to many similarities to the home audiophile crowd, there seem to be more focus on tuning the music with multi-bad equalizers.. Whereas with the audiophiles as I know them this is a big NO-NO...

I do admit, as new as I am to this forums, I am new to car audio and trying to understand what is good and what are the systems and practices to steer clear from. 



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I am here: http://maps.google.com/maps?ll=-37.998630,145.076190


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## gt6334a (Sep 9, 2010)

unfortunately car audio is slow on taking up new technology.

for example, it's very hard to currently get a head unit that plays FLAC.

i had looked around and some options that could be done now is to go with the following sources:
1. laptop w/ async USB DAC 
2. squeezebox touch (limited to files you can put on an SD card)

you can pretty much eliminate the head unit if you wish... but i think you'll need some sort of pre-amp in for volume control...

re car audio focus on equalizers: this is pretty much necessary due to the car acoustics (terrible room response compared to home).


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## blueteq (Jul 19, 2011)

Yes, FLAC is my first choice and most of my media is in Flac Format. What you mentioned gt6434a in your list was what I am finding will be the best way to get the HD music working in the car. 

So now looking for a good preamp unit, something that can handle BT connectivity for handsfree on iPhone. And do a good job in managing the signal from the source. 

Can anyone recommend a good unit with AUX in at the rear? I was looking at the Pioneer DEX-P99RS however AUX input is on the front. (3.5mm) not ideal.


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## gnesterenko (Mar 17, 2011)

blueteq said:


> Can anyone recommend a good unit with AUX in at the rear? I was looking at the Pioneer DEX-P99RS however AUX input is on the front. (3.5mm) not ideal.


If you have an iPhone and are looking at the P99RS already then you will not be needing an AUX input - that HU is apparently the only HU out there that will actually provide true bypass of the iDevice DAC without doing any DtA and AtD between the signal and the DSP. It will give you your pure connection that you desire with a 24bit AKM DAC doing the lifting, so if you can afford it, go for it. I would love to get my hands on one sometime....

Posting from work, so need this disclaimer:
"The views expressed here are mine and do not reflect the official opinion of my employer or the organization through which the Internet was accessed."


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## gt6334a (Sep 9, 2010)

i think blueteq was asking more about the iphone phone functions thru BT rather than music..

AFAIK, iphone doesn't play FLAC, it only supports apple lossless.

blueteq, we seems to be on the same frequency  i also make good use of BT for in car phone calls. it seems that if you want a BT headunit, then it limits the headunit choice (no nakamichi for example).

another option, is to get one of those standalone car/speaker phone sets that costs under <USD100... they normally clip on to the sun visor. of course you have to live with the extra step of muting your audio before receiving calls..

if you can live without a headunit, then yes a good pre-amp unit will offer better value. i don't have a specific solution in mind, but i have been looking at head-fi.org for ideas... it appears that some headphone amp/pre-amp might do the job.. some even run on 12v rails so we don't even need a power supply.. i don't have enough first-hand experience to recommend anything, but if anyone has ideas on this, i'd like to hear it.

also, gnesterenko, the p99rs is not the only head unit that can bypass the DAC. other cheaper units like alpine ida-X305, clarion, etc at about $250 range released in the past year can also do so... there were a few threads on this already in diyma and diyaudio.


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## gt6334a (Sep 9, 2010)

ohh, i forgot about rockbox, Rockbox - Open Source Jukebox Firmware. this will allow some (older) ipods to play FLAC.

however, there is no installer for iphones.


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> i think blueteq was asking more about the iphone phone functions thru BT rather than music..
> 
> AFAIK, iphone doesn't play FLAC, it only supports apple lossless.
> 
> ...


Latest developments tell that even though they bypass the dac in the device, they don't provide a digital stream all the way to the DSP (ie there is still an D to A A to D conversion process in-line). See bikinpunk test on the alpine ina-w910. It claims the same thing as all the others, is the top of the line from alpine for this year, and yet it does not do this. measured results for the outputs show quite a difference between the internal CD transport and the usb source. That would not be the case if the usb to DSP path was all digital. As the same test by bikin show on the p99rs.

For a more detailed explanation of what is going on search through my last 50 post for the keyword ina-w910 or read the whole thread on the measured result for that unit.


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## t3sn4f2 (Jan 3, 2007)

Blueteq, if you plan on doing any type of DSP processing (which I hope you would), know that all DSP units out there run at 48kHz sample rate. So It does not how "great" the source file or digital transport is, at the end, it will still get down-converted to that sample rate. Essentially leaving you with he same process that music in the studio goes through when being sent to be turn into CD. Well 3.9kHz greater though.

Don't sweat that ultra high rez stuff. You aren't going to find a DAC with an analog resolution greater then ~20bits anyways. No matter the price, home or wherever. And it's not like there is a system out there that can approach the dynamic range potential of it anyways. Well without making you go instantly deaf that is. Oh and the noise floor level in even the best recordings is no better then ~70dB (ie 70dB dynamic range).

Let's not even get into why the 44.1kHz sample rate used in standard CD audio is more then high enough for every human on this planet.

http://en.wikipedia.org/wiki/Sampling_(signal_processing)

"A partial answer is provided by the Nyquist–Shannon sampling theorem, which provides a sufficient (but not always necessary) condition under which *perfect reconstruction is possible*. The sampling theorem guarantees that *bandlimited signals *(i.e., signals which have a maximum frequency) *can be reconstructed perfectly from their sampled version, if the sampling rate is more than twice the maximum frequency.* Reconstruction in this case can be achieved using the Whittaker–Shannon interpolation formula."


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## gt6334a (Sep 9, 2010)

t3sn4f2 said:


> Latest developments tell that even though they bypass the dac in the device, they don't provide a digital stream all the way to the DSP (ie there is still an D to A A to D conversion process in-line). See bikinpunk test on the alpine ina-w910.


wow, thanks for the info. i had missed that particular thread (http://www.diymobileaudio.com/forum/bikinpunks-product-review-forum/107814-pioneer-p99rs-pioneer-deh-p9-pioneer-800prs-testing-2.html) somehow... 

i had thought of going with and iDevice in the past but now it's pretty clear there isn't much to gain for me (as i don't already have an iDevice)..


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## gt6334a (Sep 9, 2010)

hmm, reviewing back the differences between the CD and ipod measurements of the w910; i am not sure if i agree that this is due to additional DA-AD conversion.

the measurements look a little bit different, but to me it's not that big. i would expect a bigger degradation if there are basically 2 additional cheap chips (haha they rhyme...) doing the extra conversion.

i am not sure, but have you all considered that the drop in performance may come from jitter effects instead? it's plausible that the cd may have better better clocking and thus reduced jitter..

also regarding the Nyquist theorem basically is an effect of DFT. the sampled signal will have copies exactly 2*fsample apart. at least this is what i still remember from the theory, i don't have my notes with me.. 

So, basically if you have freqs of interest that are higher than double your sampling frequency, you have guaranteed that your sample is messed up..

so while the nyquist theorem states that it is possible to accurately reconstruct your original signal if you met the 2*fsample criterion, it is not a guarantee that you will.. the keyword is "possible". 

so other effects, like jitter for example, may still affect your signal.

also, why 96khz might still offer some sonic benefits? it is demonstrated for example in the study below that humans can, in a good env (i guess not in a running car tho....) can differentiate between 44.1khz and 88.2 khz samples in blind test. i don't think we have a model that fully explains this, but the fact is observable:


> It is currently common practice for sound engineers to record digital music using high-resolution formats, and then down sample the files to 44.1kHz for commercial release. This study aims at investigating whether listeners can perceive differences between musical files recorded at 44.1kHz and 88.2kHz with the same analog chain and type of AD-converter. Sixteen expert listeners were asked to compare 3 versions (44.1kHz, 88.2kHz and the 88.2kHz version down-sampled to 44.1kHz) of 5 musical excerpts in a blind ABX task. Overall, participants were able to discriminate between files recorded at 88.2kHz and their 44.1kHz down-sampled version. Furthermore, for the orchestral excerpt, they were able to discriminate between files recorded at 88.2kHz and files recorded at 44.1kHz.
> 
> Authors: Pras, Amandine; Guastavino, Catherine
> Affiliation: McGill University, Montreal, Quebec, Canada
> ...



anyhow, thanks to the folks here particularly bikinpunk for the good effort in doing these measurements.. i find that my previous assumptions on using an iDevice were wrong. before i purchased anything and discovered it to my dismay


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## blueteq (Jul 19, 2011)

Well I heard many people tell me the human ear cannot pickup on the difference, and not knowing that much about sample rates and bit rates I can tell the difference between a CD and the same track played from a 24/96 and then a difference yet again when you go to 24/192. This is with my Linn MajikDS at home one of Linn's entry products capable of playing 24/192, and with it I got some sample tracks to show what HD music do compared to compressed and other formats. 

Not talking about the music, if you have something that is sampled at a higher rate (more samples than less, not frequency) it will reproduce a better copy? 
So in my view, the human ear might not be able hear the difference I do belief it has a big impact on the over quality, by providing more information for playback. 
This is why I belief that even if a car is not the best place to listen to music, i.e. you cannot control the noise or speaker placement, the higher quality music played it will sound better. 

GT, Bluetooth is a must yes, nothing as handy to just press a button and start taking. I recently started to use the voice dialing on the iPhone and once you get to say the names in the way the phone wants to hear it... Works like a charm. 
And I just got my wife one of those BlueAnts kits and it's not as good as having it in the HU. 

As for the FLAC on the iPhone, someone actually released a FLAC player on the app store, check it out, not easy to manage your library but works well. 
With the FLAC plugged into my current HU, Eclipse AVN726ea using the IPhone adapter there is a BIG difference in quality compared to AAC and MP3 tracks. I do know that the iPhone hardware is limited to 16/44...


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## blueteq (Jul 19, 2011)

gnesterenko said:


> If you have an iPhone and are looking at the P99RS already then you will not be needing an AUX input - that HU is apparently the only HU out there that will actually provide true bypass of the iDevice DAC without doing any DtA and AtD between the signal and the DSP. It will give you your pure connection that you desire with a 24bit AKM DAC doing the lifting, so if you can afford it, go for it. I would love to get my hands on one sometime....
> 
> Posting from work, so need this disclaimer:
> "The views expressed here are mine and do not reflect the official opinion of my employer or the organization through which the Internet was accessed."


If I am getting this correctly, I have a track on the IDevice plugged into the Pioneer iPod adapter it will take the mp3 or AAC track directly from the iDevice and decode it within the HU? This would of been ideal if the P99RS supported FLAC!


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> hmm, reviewing back the differences between the CD and ipod measurements of the w910; i am not sure if i agree that this is due to additional DA-AD conversion.
> 
> *the measurements look a little bit different, but to me it's not that big. i would expect a bigger degradation if there are basically 2 additional cheap chips (haha they rhyme...) doing the extra conversion.
> 
> ...


Thanks for the info.

As for the ina results, whenever I've compared analog output results of my soundcard while using different external or internal digital sources, they always come out near identical. Numbers are almost the same and no different then run to run discrepancies. graph are identical on all parts but the noise floor which also fluctuates from test run to test run (even when the source does not change). (That would also take jitter out of the equation for these type of measurements. But that can be easily shown by using two different digital sources on the head unit, ie ipod and thumb drive) 

You can see an example of this in the p99rs test post below.....

http://www.diymobileaudio.com/forum/bikinpunks-product-review-forum/107814-pioneer-p99rs-pioneer-deh-p9-pioneer-800prs-testing.html

*Quote shortened to fit on my post full post in link above*



bikinpunk said:


> Here's some test results for the Pioneer P99RS in CD and iPod out. Also, I did a test on the 800PRS to see how it compares to the P99. Results are listed as noted below.
> 
> 
> Thanks to JCollins for donating his P99 for testing. I made certain not to hot swap anything. These units were always powered down before swapping out rca's. Live and learn.
> ...



Compare that to even just the summary, and there is something way uncommon going on.

http://www.diymobileaudio.com/forum/bikinpunks-product-review-forum/108165-alpine-ina-w910-vs-alpine-iva-w505.html

*Quote shortened to fit on my post full post in link above*



bikinpunk said:


> *CD as Source:*
> 
> Summary:



*iPod as Source:*

Summary:









Another thing that point to my conclusion is that the ina-w910 will not output the ipod source out to the H800 through the Toslink port. It only goes out AiNet.

Sorry for the OT Blue, and thanks for the measurements Erin ("bikinpunk").


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## rain27 (Jan 15, 2009)

The only 24/96 or 24/192 set up I know of would need a source unit not necessarily made for the car. A media player like the Squeezebox Touch, Mac Mini/PC, etc.

The newest version of the BitOne is supposed to have high resolution and Audison Thesis amps and the upcoming Voce amps I believe have 24/192 DACs.

Again, whether you could tell the difference in a test is questionable and has never been accomplished in an actual testing environment. It would seem to have more merit compared to differences in cd players, but there is no evidence of either.


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## gt6334a (Sep 9, 2010)

blueteq said:


> If I am getting this correctly, I have a track on the IDevice plugged into the Pioneer iPod adapter it will take the mp3 or AAC track directly from the iDevice and decode it within the HU? This would of been ideal if the P99RS supported FLAC!


since this is digital signal going into the dac, it's PCM. meaning it's downstream from the the ipod's decoding of whatever compression format (aac, mp3, alac, flac etc).

so, this could work for you, IF you can live with the limitations of the iphone flac player that you mentioned and the disk space limit of the iphone.

i seriously think the cleaner option though, is using the squeezebox touch as it can connect to SD and also an *external HD*! Basically you can sync it with your 1Tb collection @home.

not sure if you are aware, but the squeezebox devices take 5v DC at 2A. so you can power it with a cig lighter inverter, or DC-DC power supply..


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## gt6334a (Sep 9, 2010)

t3sn4f2 said:


> Thanks for the info.


i am glad that you find it useful



t3sn4f2 said:


> As for the ina results, whenever I've compared analog output results of my soundcard while using different external or internal digital sources, they always come out near identical. Numbers are almost the same and no different then run to run discrepancies.


on your tests, did you use the same input to your soundcard? because in that case the clock mechanism would've been the same and this would explain the similar response.

what i see with the head unit is that there might be a superior clock mechanism in the unit for data coming out of the cd player.

and then alpine might have used an inferior usb chip or buffer mechanism. so now, the data coming from the usb side is a lot 'dirtier'....

again, a lot depends on implementation. in theory async USB is better than adaptive but i have read cases where it is not and it's due to poor implementation.




t3sn4f2 said:


> Another thing that point to my conclusion is that the ina-w910 will not output the ipod source out to the H800 through the Toslink port. It only goes out AiNet.


Now this is interesting... i don't have an explanation for this.


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> *since this is digital signal going into the dac, it's PCM. meaning it's downstream from the the ipod's decoding of whatever compression format (aac, mp3, alac, flac etc).*
> 
> so, this could work for you, IF you can live with the limitations of the iphone flac player that you mentioned and the disk space limit of the iphone.
> 
> ...


-To add to this, all external USB boxes convert from digital to analog internally and transmit in analog via the bus cable [ainet, ipbus (?)]. 

-HRT tech is coming out with a mobile PS for their hrt istreamers that is rated at 5 volts and 2.1 amps also. Should work great for this app. It looks like a little cigarette adapter plug with a usb port on the back. Only $14 also.

Although, I think this one could work better (if it can be made to work that is). It can send a trigger pulse to the hardwired button on these digital sources that need to be turned on each time you power up. Or to the DAC down stream that need to come on after the digital source to sync properly. I dunno, just thinking out loud.


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> on your tests, did you use the same input to your soundcard? because in that case the clock mechanism would've been the same and this would explain the similar response.
> 
> what i see with the head unit is that there might be a superior clock mechanism in the unit for data coming out of the cd player.
> 
> ...


My card has a selectable sync source setting. It was set to external when I ran the test. 

I'll try and redo the test today with two different digital sources I have (old Sony DVD player and a Pure i-20 iPod dock). Just to make sure I didn't forget and am mistaken in these claimed results (I do _alot_ of these experimentations )


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## gt6334a (Sep 9, 2010)

t3sn4f2 said:


> -To add to this, all external USB boxes convert from digital to analog internally and transmit in analog via the bus cable [ainet, ipbus (?)].


not sure what you are referring to here, the ipod, or squeezebox touch?

the squeezebox touch treats the external usb hard drive much like a computer would. audio conversion is done within the sqeezebox and it can output either analog, or digital (coax, or optical).



t3sn4f2 said:


> Although, I think this one could work better (if it can be made to work that is).


 cool! this one can even step up to 24v...


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> not sure what you are referring to here, the ipod, or squeezebox touch?
> 
> the squeezebox touch treats the external usb hard drive much like a computer would. audio conversion is done within the sqeezebox and it can output either analog, or digital (coax, or optical).



Never mind, I lost track of the thread and took Blue's "adapter" wording in your quote as him wanting to use an old external usb box for the head unit instead. :blush:


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> cool! this one can even step up to 24v...


Powerstream.com also has high quality dc to dc converters.


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## rain27 (Jan 15, 2009)

The Squeezebox Touch has basically everything you could want in a media player: 24 bit AKM DAC (like the P99RS), touchscreen, great remote, nice menu system, quality screen, coax and optical, rca, sd card, external hard drive, etc. 

The problem is that the software has been buggy in my experience. If a software update or two can fix the issues, it would be a great player.


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## kmarei (Nov 13, 2009)

The iPhone CAN play FLAC files
Download an app called 
Wait for it
FLAC Player 
9.99 but I've tried it and the sound is much better than mp3 at 320
But same was wav, which the iPhone natively supports


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## t3sn4f2 (Jan 3, 2007)

t3sn4f2 said:


> My card has a selectable sync source setting. It was set to external when I ran the test.
> 
> *I'll try and redo the test today with two different digital sources I have (old Sony DVD player and a Pure i-20 iPod dock). * Just to make sure I didn't forget and am mistaken in these claimed results (I do _alot_ of these experimentations )


K here it is.........

Below are 4 RMAA test results of 4 different digital sources all feeding the same DAC and ADC (ie the output and input of my soundcard connected together to form a loopback chain; EMU-0404PCI. 

Digital sources:

-Pure i-20 digital iPod dock connected via Toslink S/PDIF, and with the soundcard set to external sync.

-Sony DVD-NS400D DVD Player connected and setup in the same way as the Pure dock.

-Foobar2000 Media player outputting an ASIO stream to the soundcard. No digital connection or S/PDIF format here, just a digital stream from the PC to the internal soundcard DSP. Sync set to internal this time, as it should be.

-iTunes outputting a WDM stream to the soundcard. No digital connection or S/PDIF format here, just a digital stream from the PC to the internal soundcard DSP. Sync set to internal this time, as it should be.

I only posted the summary results and one complex test graph which should be enough to show what we are looking for.

Summary:









IMD:









You can see that even with 4 different digital sources, the results are nearly identical and any negligible differences are due to analog variation from each test run or from image creation artifact (for the graph portion). And these variables are in the noise floor only, the high level signals are identical. It's hard to tell how each result is on the graph since it is covered by the next but I can grantee you that anything weird is on each one of the results. The mass around the base of the fundamental tone in the IMD graph would be a good example 

From this I think we can conclude that if the USB input on a head unit is implemented as we expect. Then the differences between USB and the internal transport, _on these type of measurements_, would be no where near as different as they are in the INA-W910's. At the very least.


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## gt6334a (Sep 9, 2010)

t3sn4f2 said:


> You can see that even with 4 different digital sources, the results are nearly identical and any negligible differences are due to analog variation from each test run or from image creation artifact (for the graph portion).


thanks for taking the time to do this.. yes, it looks like 4 devices have performance equal to or greater than your soundcard... 

pretty good performance for the Pure i-20, which is <$100...



t3sn4f2 said:


> From this I think we can conclude that if the USB input on a head unit is implemented as we expect. Then the differences between USB and the internal transport, _on these type of measurements_, would be no where near as different as they are in the INA-W910's. At the very least.


there is definitely something amiss in alpine's implementation on the w910. what it is exactly, i don't think we can pinpoint unless someone has a photo of the board and we can try and see what chips are there.. 

the simplest explanation, to me is that the chips upstream of the dac (the ones that convert the usb data signal, the data buffer, or the clock etc) are not up to the performance of the downstream DAC and output stage.

anyhow from a practical perspective, i saw you asked in the w901 vs w505 thread whether running the ipod thru AUX would yield better performance. i am also interested to know this.

also, it would be interesting to compare against the performance of the IDA X305, which is CD-less.. I did find a review (PASMAG | PERFORMANCE AUTO AND SOUND - Alpine IDA-X305 Digital Media Receiver - PAGE 2) that had some measurements but it was simple freq response curves... the rest were just too smeared out for me to read...


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## t3sn4f2 (Jan 3, 2007)

gt6334a said:


> there is definitely something amiss in alpine's implementation on the w910. what it is exactly, i don't think we can pinpoint unless someone has a photo of the boar and we can try and see what chips are there..
> 
> the simplest explanation, to me is that the chips upstream of the dac (the ones that convert the usb data signal, the data buffer, or the clock etc) are not up to the performance of the downstream DAC and output stage


I'll agree. 



gt6334a said:


> also, it would be interesting to compare against the performance of the IDA X305, which is CD-less.. I did find a review (PASMAG | PERFORMANCE AUTO AND SOUND - Alpine IDA-X305 Digital Media Receiver - PAGE 2) that had some measurements but it was simple freq response curves... the rest were just too smeared out for me to read...


Good data, thanks. I'll take a better look at it tomorrow.


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