Chord Mojo DAC-amp ☆★►FAQ in 3rd post!◄★☆
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Hi Mojo lovers,

I use my Mojo for more than a year and I am very happy with it. My source is an Iphone 6s with Tidal and I use the USB input of the Mojo. Once I tried Mojo driven by my Heed Audio CD transport thru optical cable and the SQ was significantly better. I am wondering if the difference is due to the better digital source or due to optical instead of USB input of Mojo. Because of this I started thinking about to try an USB SPDIF converter.
So my question to you guys:
Do anyone use an USB SPDIF converter with Mojo? If yes does it improves the SQ?
Thanks!
Pretty sure the increase in sound quality is sample rate. I only get 44Khz out of my iPhone 6S and iPad using Tidal and 768 or 384 from my MacBook Pro the color chart is hard to tell the difference.
 
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Pretty sure the increase in sound quality is sample rate. I only get 44Khz out of my iPhone 6S and iPad using Tidal and 768 or 384 from my MacBook Pro the color chart is hard to tell the difference.
CD also maxes out at 16/44.1 kHz.
 
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That would answer the question whether the poly + mojo produces better SQ results than the mojo + usb cable.

What about the other question: Shouldn't a USB-SPDIF-converter produce the same effect as the Poly since both options (USB-SPDIF-converter and Poly) eliminate the USB cable and replace it with a optical cable (I have read somewhere that the Poly transports the digital signal via an optical cable to the Mojo). I am asking because there are pretty inexpensive and compact USB-SPDIF-converters which could produce the same results as the Poly for far less money. This conclusion is based on the assumption I described in the post you replied to which is that the only thing that matters is that the digital signal is fed to the mojo by an optical cable. This conclusion would also imply that there is no other quality a USB-SPDIF-converter would have to have and that any (cheap) USB-SPDIF-converter would do.

I appreciate anyone who can find a fault in my argument.

@miketlse do you have the link to the post which refuted the critique I cited?
You have confused me there - which specific critique are you referring to?
 
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musickid

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I use kabeldirekt for my mojo/imac. A very solid performer, guitar strings sound eerily real. Also don't forget an ill engineered usb to coax/optical convertor has the potential to completely mess up the timing of any original signal inputted into it. In this case you would be listening to distorted music without realising and i think this may apply to cheap and/or expensive solutions. I underline may here as this doesn't apply to all convertors and i have no idea how to differentiate between them. Using optical straight from a pc/mac is best if you have the option to. My opinion here if that helps.
 
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What about the other question: Shouldn't a USB-SPDIF-converter produce the same effect as the Poly since both options (USB-SPDIF-converter and Poly) eliminate the USB cable and replace it with a optical cable (I have read somewhere that the Poly transports the digital signal via an optical cable to the Mojo). I am asking because there are pretty inexpensive and compact USB-SPDIF-converters which could produce the same results as the Poly for far less money. This conclusion is based on the assumption I described in the post you replied to which is that the only thing that matters is that the digital signal is fed to the mojo by an optical cable. This conclusion would also imply that there is no other quality a USB-SPDIF-converter would have to have and that any (cheap) USB-SPDIF-converter would do.

I appreciate anyone who can find a fault in my argument.

@miketlse do you have the link to the post which refuted the critique I cited?
It depends on the USB audio implementation. In case of Poly, the usb audio out is dedicated, it doesn't perform other functions on the usb data bus (except may be reading the sd-card). In case of Phones and laptops, usb bus is shared for variety of other functions and their PCB is crowded with other components. For these sources, adding a USB-SPDIF converter is not going to help, since it's just converting the noisy data to optical format. If you like optical, check out A&K DAPs.
 
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Imac's have a high quality spdif optical out built in to the headphone jack. Surprisingly the on board dac is not low quality by any means but of course cannot compete with mojo. It's optical out does in my opinion rival any convertor.
 
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It depends on the USB audio implementation. In case of Poly, the usb audio out is dedicated, it doesn't perform other functions on the usb data bus (except may be reading the sd-card). In case of Phones and laptops, usb bus is shared for variety of other functions and their PCB is crowded with other components. For these sources, adding a USB-SPDIF converter is not going to help, since it's just converting the noisy data to optical format. If you like optical, check out A&K DAPs.
It's not converting "dirty USB data to dirty coax data" The whole point is that it's stripping out the electrical noise and passing along a cleanly clocked, data only source.
 
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upload_2018-4-4_12-3-36.png
Now i bet the contents of that bag is filthy!!:floatsmile:
 
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I use kabeldirekt for my mojo/imac. A very solid performer, guitar strings sound eerily real. Also don't forget an ill engineered usb to coax/optical convertor has the potential to completely mess up the timing of any original signal inputted into it. In this case you would be listening to distorted music without realising and i think this may apply to cheap and/or expensive solutions. I underline may here as this doesn't apply to all convertors and i have no idea how to differentiate between them. Using optical straight from a pc/mac is best if you have the option to. My opinion here if that helps.
It depends on the USB audio implementation. In case of Poly, the usb audio out is dedicated, it doesn't perform other functions on the usb data bus (except may be reading the sd-card). In case of Phones and laptops, usb bus is shared for variety of other functions and their PCB is crowded with other components. For these sources, adding a USB-SPDIF converter is not going to help, since it's just converting the noisy data to optical format. If you like optical, check out A&K DAPs.
It's not converting "dirty USB data to dirty coax data" The whole point is that it's stripping out the electrical noise and passing along a cleanly clocked, data only source.
Thanks for all of your input.
I didn't know about the timing issues with USB-SPDIF converter.

I see the following options to connect a source with the mojo:

(a) Android Smartphone which connects to the Mojo via USB cable. Additional investment required: USB OTG micro B - B cable (5$ to 150$)
(b) DAP which connects to the Mojo via an optical cable. Additional investment required: Ibasso DX80 (cheapest DAP I found with optical out) for 200 USD used + 15-100$ for the Toslink cable (e.g. the lifatec toslink cable for 90$).
(c) USB-SPDIF converter which connects the source via USB first and then via optical or coaxial to the Mojo. Additional investment required: I have seen USB-SPDIF converters ranging from 20$ to 120$ for the Schiit Eitr to....
(d) Chord Poly which connects to the Mojo via optical cable (I read somewhere that the data transfer from poly to Mojo is via optical but I can't find that reference any more). Additional investment required: 400$ used.
(e) Less viable options: PC (Lenovo Laptop) is not really an option because it has more noise than a smartphone and no optical out. The conventional/cheap DAPs I have (Sansa Clip, Sony, Samsung; all no optical out) don't seem to provide any benefit over (a) and have worse UI.

Advantages and disadvantages as I see them for the options above:
(a)
+ cheapest
+ most compact (no additional unit)
- noisy USB cable which may decrease SQ, the theory is that of course bits are bits but RF noise is audible, see FAQ in https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/ (Spoiler: Is one the the inputs better than the other?)

(b)
+ optical cable should sound best (compared to coax and usb) also acc. to Rob Watts (designer of Mojo), see http://www.the-ear.net/how-to/rob-watts-chord-mojo-tech
- more expensive than (a) by ~ 200$.
- a little less compact than (a) because of an additional unit

(c)
- I am confused by the above feedback: My original assumption was that what matters is that there is an optical input to the mojo and nothing else really matters and a USB-SPDIF converter would provide for that. But if there is a timing issue as described here https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-2386#post-14149141 and other issues as described here https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-2386#post-14149215 then this might not be an option because it's more expensive than (a) but might produce worse SQ than (a).
+ But it could be a great solution as there are compact, inexpensive USB-SPDIF converters. The effect on SQ of such an USB-SPDIF converter is just unclear to me at this point.
- If quality of these units matters in some way and it's not only as simple as "SQ is great as long as there is an optical cable feeding the mojo" than the selection of quality units gets smaller and less compact possibly, the Schiit Eitr for example is already not really portable anymore.

(d)
+ Should sound at least as good as (b) given that it uses an optical connection to transfer data to the mojo (I forgot where I read that. Would be nice if someone had a link to confirm that). I am not sure if there are other factors that effect sound quality built into the Poly other than the fact that the mojo is fed by an optical connection.
- This post https://www.head-fi.org/threads/chord-electronics-☆-poly-☆-wireless-microsd-module-for-mojo-☆★►useful-info-on-1st-page-◄★☆.831347/page-34#post-13161612 put forth a few arguments that the Poly could be noisy in itself and effect SQ negatively. I have not seen a rebuttal to that. Has anyone?
- more expensive than (a) by ~ 300$.
- a little less compact than (a) because of an additional unit

My criteria are (from important to not so important but still relevant): Audible sound quality, compactness (I live in hotels mostly), price.
 
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Imac's have a high quality spdif optical out built in to the headphone jack. Surprisingly the on board dac is not low quality by any means but of course cannot compete with mojo. It's optical out does in my opinion rival any convertor.
I'm using my HUGO via Mac Mini's (late 2012), and they're good. Too bad, apple has dropped Optical out since 2016 refresh.
 
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I use optical from a 2013 512gb ssd imac it is excellent. I investigated this and i think apple spdif is a high quality texas instruments or cirrus logic reputable brand. With optical out from computer i know i am getting the right data and timing with non of the corruption a convertor might introduce. IMHO don't go down the convertor route no matter how nicely it is wrapped up unless there is no other option. I don't trust the rf noise they inject.
 
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Thanks for all of your input.
I didn't know about the timing issues with USB-SPDIF converter.

I see the following options to connect a source with the mojo:

(a) Android Smartphone which connects to the Mojo via USB cable. Additional investment required: USB OTG micro B - B cable (5$ to 150$)
(b) DAP which connects to the Mojo via an optical cable. Additional investment required: Ibasso DX80 (cheapest DAP I found with optical out) for 200 USD used + 15-100$ for the Toslink cable (e.g. the lifatec toslink cable for 90$).
(c) USB-SPDIF converter which connects the source via USB first and then via optical or coaxial to the Mojo. Additional investment required: I have seen USB-SPDIF converters ranging from 20$ to 120$ for the Schiit Eitr to....
(d) Chord Poly which connects to the Mojo via optical cable (I read somewhere that the data transfer from poly to Mojo is via optical but I can't find that reference any more). Additional investment required: 400$ used.
(e) Less viable options: PC (Lenovo Laptop) is not really an option because it has more noise than a smartphone and no optical out. The conventional/cheap DAPs I have (Sansa Clip, Sony, Samsung; all no optical out) don't seem to provide any benefit over (a) and have worse UI.

Advantages and disadvantages as I see them for the options above:
(a)
+ cheapest
+ most compact (no additional unit)
- noisy USB cable which may decrease SQ, the theory is that of course bits are bits but RF noise is audible, see FAQ in https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/ (Spoiler: Is one the the inputs better than the other?)

(b)
+ optical cable should sound best (compared to coax and usb) also acc. to Rob Watts (designer of Mojo), see http://www.the-ear.net/how-to/rob-watts-chord-mojo-tech
- more expensive than (a) by ~ 200$.
- a little less compact than (a) because of an additional unit

(c)
- I am confused by the above feedback: My original assumption was that what matters is that there is an optical input to the mojo and nothing else really matters and a USB-SPDIF converter would provide for that. But if there is a timing issue as described here https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-2386#post-14149141 and other issues as described here https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-2386#post-14149215 then this might not be an option because it's more expensive than (a) but might produce worse SQ than (a).
+ But it could be a great solution as there are compact, inexpensive USB-SPDIF converters. The effect on SQ of such an USB-SPDIF converter is just unclear to me at this point.
- If quality of these units matters in some way and it's not only as simple as "SQ is great as long as there is an optical cable feeding the mojo" than the selection of quality units gets smaller and less compact possibly, the Schiit Eitr for example is already not really portable anymore.

(d)
+ Should sound at least as good as (b) given that it uses an optical connection to transfer data to the mojo (I forgot where I read that. Would be nice if someone had a link to confirm that). I am not sure if there are other factors that effect sound quality built into the Poly other than the fact that the mojo is fed by an optical connection.
- This post https://www.head-fi.org/threads/chord-electronics-☆-poly-☆-wireless-microsd-module-for-mojo-☆★►useful-info-on-1st-page-◄★☆.831347/page-34#post-13161612 put forth a few arguments that the Poly could be noisy in itself and effect SQ negatively. I have not seen a rebuttal to that. Has anyone?
- more expensive than (a) by ~ 300$.
- a little less compact than (a) because of an additional unit

My criteria are (from important to not so important but still relevant): Audible sound quality, compactness (I live in hotels mostly), price.
If you don't want to spend much - (a)
If you don't want to spend much + you can live without streaming - (a) with phone in airplane mode during playback.
If you can spend a bit - (d) By your estimation only $100 difference vs (b). Definitely go for Poly. It's more compact than all the other 3. You have to just charge one device (Mojo + Poly), since they merge perfectly into one unit. Poly uses USB not optical to interface with Mojo. Since it's purpose built for Audio out, you don't have to worry about SQ. Also, since it's network based, you're not tied to one music library.
 
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Thanks for all of your input.
I didn't know about the timing issues with USB-SPDIF converter.

I see the following options to connect a source with the mojo:

(a) Android Smartphone which connects to the Mojo via USB cable. Additional investment required: USB OTG micro B - B cable (5$ to 150$)
(b) DAP which connects to the Mojo via an optical cable. Additional investment required: Ibasso DX80 (cheapest DAP I found with optical out) for 200 USD used + 15-100$ for the Toslink cable (e.g. the lifatec toslink cable for 90$).
(c) USB-SPDIF converter which connects the source via USB first and then via optical or coaxial to the Mojo. Additional investment required: I have seen USB-SPDIF converters ranging from 20$ to 120$ for the Schiit Eitr to....
(d) Chord Poly which connects to the Mojo via optical cable (I read somewhere that the data transfer from poly to Mojo is via optical but I can't find that reference any more). Additional investment required: 400$ used.
(e) Less viable options: PC (Lenovo Laptop) is not really an option because it has more noise than a smartphone and no optical out. The conventional/cheap DAPs I have (Sansa Clip, Sony, Samsung; all no optical out) don't seem to provide any benefit over (a) and have worse UI.

Advantages and disadvantages as I see them for the options above:
(a)
+ cheapest
+ most compact (no additional unit)
- noisy USB cable which may decrease SQ, the theory is that of course bits are bits but RF noise is audible, see FAQ in https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/ (Spoiler: Is one the the inputs better than the other?)

(b)
+ optical cable should sound best (compared to coax and usb) also acc. to Rob Watts (designer of Mojo), see http://www.the-ear.net/how-to/rob-watts-chord-mojo-tech
- more expensive than (a) by ~ 200$.
- a little less compact than (a) because of an additional unit

(c)
- I am confused by the above feedback: My original assumption was that what matters is that there is an optical input to the mojo and nothing else really matters and a USB-SPDIF converter would provide for that. But if there is a timing issue as described here https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-2386#post-14149141 and other issues as described here https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-2386#post-14149215 then this might not be an option because it's more expensive than (a) but might produce worse SQ than (a).
+ But it could be a great solution as there are compact, inexpensive USB-SPDIF converters. The effect on SQ of such an USB-SPDIF converter is just unclear to me at this point.
- If quality of these units matters in some way and it's not only as simple as "SQ is great as long as there is an optical cable feeding the mojo" than the selection of quality units gets smaller and less compact possibly, the Schiit Eitr for example is already not really portable anymore.

(d)
+ Should sound at least as good as (b) given that it uses an optical connection to transfer data to the mojo (I forgot where I read that. Would be nice if someone had a link to confirm that). I am not sure if there are other factors that effect sound quality built into the Poly other than the fact that the mojo is fed by an optical connection.
- This post https://www.head-fi.org/threads/chord-electronics-☆-poly-☆-wireless-microsd-module-for-mojo-☆★►useful-info-on-1st-page-◄★☆.831347/page-34#post-13161612 put forth a few arguments that the Poly could be noisy in itself and effect SQ negatively. I have not seen a rebuttal to that. Has anyone?
- more expensive than (a) by ~ 300$.
- a little less compact than (a) because of an additional unit

My criteria are (from important to not so important but still relevant): Audible sound quality, compactness (I live in hotels mostly), price.
The reason I went with a Schiit Eitr is that they seem to have their heads wrapped around the USB interface quite well, and all the reviews were quite complementary. Even to the point of suggesting that it makes absolutely no difference what you feed the Eitr with, either way it'll output the same correctly clocked, clean data stream to your device, and my tests prove the same thing so far.

Being able to plug any dirty USB source, from my Nexus 6P, to my Lenovo Yoga, to a tablet, or my dedicated desktop source, they'll all sound the same.
 
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