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RP4 USB ports... good enough?
#1
Big Grin 
Hi, Guys,
This is my first post on this forum!
I have been playing with Volumino for a couple of days and I'm also going to give Moode a try as soon as I pick up another SD card. I've tried running my RP4 into my external DAC (the L2 DAC in my Vinnie Rossi LIO integrated amp) and to be honest, I'm shocked at how good it sounds... and this is just streaming Spotify... I haven't even gotten around to feeding it any of my hi-res files.
My question: Does anyone have experience comparing the on-board RP4 USB ports as a transport to a DAC vs. the sound quality of an add-on board like the Allo DigiOne or DigiOne Signature, or something similar? 
Wondering if it pays to try coaxial (SPDIF) with one of those HATs.
Many thanks,

Steve
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#2
I use the USB port on my Pi 4 to feed an Emotive Stealth DC-1 DAC.  I see no reason to suspect that the USB ports on the R-Pi-4 would somehow produce lower quality, or different, zeroes and ones than would a coaxial S/PDIF hat.  

I recommend the following article:
https://www.audiosciencereview.com/forum...tter.1943/

From that article:


Quote:Conclusions
As seen from pure measurement point of view, there was no case where USB was worst than S/PDIF. Indeed the reverse was true in that S/PDIF was noisier in some DACs. So the default assumption that somehow S/PDIF has some advantage over USB is simply false.

Given the convenience of USB when using computers and networked audio players and streamers, I see no reason to use S/PDIF. You get a superior architecture with no need to get yet another dongle to create S/PDIF out of your computer.

The other great thing about USB is that it will be here for all time. It is so prevalent in computer world that it has no chance of dying.

Not covered is higher functionality of USB with respect to support for uncompressed multichannel, DSD, etc. and using USB becomes a no brainer.
Cheers,
  Miss Sissy Princess
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#3
(03-24-2021, 05:59 PM)Miss Sissy Princess Wrote: This is actually quite helpful, thank you!


I use the USB port on my Pi 4 to feed an Emotive Stealth DC-1 DAC.  I see no reason to suspect that the USB ports on the R-Pi-4 would somehow produce lower quality, or different, zeroes and ones than would a coaxial S/PDIF hat.  

I recommend the following article:
https://www.audiosciencereview.com/forum...tter.1943/

From that article:


Quote:Conclusions
As seen from pure measurement point of view, there was no case where USB was worst than S/PDIF. Indeed the reverse was true in that S/PDIF was noisier in some DACs. So the default assumption that somehow S/PDIF has some advantage over USB is simply false.

Given the convenience of USB when using computers and networked audio players and streamers, I see no reason to use S/PDIF. You get a superior architecture with no need to get yet another dongle to create S/PDIF out of your computer.

The other great thing about USB is that it will be here for all time. It is so prevalent in computer world that it has no chance of dying.

Not covered is higher functionality of USB with respect to support for uncompressed multichannel, DSD, etc. and using USB becomes a no brainer.
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#4
Thank you for taking the time to write back. I'm glad that I could be of some assistance.
Cheers,
  Miss Sissy Princess
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#5
I've used an SPDIF hat, and a hat dac on an RPI 3B+, and and RPI 4B with a hat dac and with a USB dac. In every case, I think the dac's characteristics outweigh the connection type. I haven't made the comparison with USB on a pre-RPI 4 cpu, but I suspect that the old combo ethernet/USB did have the negative effects many have cited.

I would answer 'yes' to your question.
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#6
(03-24-2021, 07:25 PM)Skip Pack Wrote: I would answer 'yes' to your question.

Why?
Cheers,
  Miss Sissy Princess
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#7
Because I suspect that the higher quality dac or the dac better suited to your system will sound better via any (spdif, i2s, or USB) connection method then a dac that is less well suited. It's not that the connection is not important, just that the dac differences are more determinent. The OP's 'good enough' is guidance I am following here.
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#8
(03-24-2021, 08:38 PM)Skip Pack Wrote: Because I suspect that the higher quality dac or the dac better suited to your system will sound better via any (spdif, i2s, or USB) connection method then a dac that is less well suited. It's not that the connection is not important, just that the dac differences are more determinent. The OP's 'good enough' is guidance I am following here.

Thanks for the clarification.  We are in agreement.

I thought that you were answering "Wondering if it pays to try coaxial (SPDIF) with one of those HATs."  There are some very nice external DACs, including the spectacular Topping E30, available for less than the $239 cost of the Allo DigiOne Signature S/PDIF interface hat.
Cheers,
  Miss Sissy Princess
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#9
There i only one point of attention. Raspberry usb ports and Ethernet port shares the same bus. So if you are using both together could be an issue. But never tested this scenario.
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#10
(03-30-2021, 12:34 PM)officialsm Wrote: There i only one point of attention. Raspberry usb ports and Ethernet port shares the same bus. So if you are using both together could be an issue. But never tested this scenario.

Well, I understand that this was the case (sharing the bus) in earlier models, but not with the 4. In any event, I have decided to do an experiment. I purchased the Allo USBridge Signature. It will probably take a couple of weeks to get here. When it does, I will do a head to head comparison between the two USB solutions and let everybody know what I’m hearing.

:-)

Steve
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