DCAudioDIY.com

Looking at the Sonore website, I'd have to say it depends on how you have it configured.... It can just pull files from an SMB share and do the rendering & output the music to the USB port, or it can just be a bit-shuffler for an external renderer. So, for example if you have a bunch of music on a NAS, you don't NEED any software to play music, you can use the built-in capabilities of the Sonore device to play the files on a USB DAC, and it would appear that the Sonore device can convert formats your DAC can't handle to ones it can on the fly. You may need to define that in the Sonore configuration for some DACS, others it can figure out on its own. Or, you could use some other music server software (like foobar2000, although I'm not sure foobar2000 would work for this application), on your NAS, or somewhere else on the network, to do the rendering and the Sonore looks like an Ethernet connected playback device to the renderer and just spits out whatever bits the renderer sends it to the USB DAC.

Hope that's slightly clearer than mud...

Roscoe

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So a renderer is not really rendering. Interesting. I assume Sonore running on a tablet doesn't actually touch the data at all.

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All equipment is referenced to a common ground, or it should be. Power supply noise is not just on the rails, it's on ground. Different power supplies will have different amounts of noise, and motherboards will have different power supply decoupling. There's noise everywhere.

The problem with non blind tests is it's easy to hear what you want to or think you should hear. This is true with pretty much anything - wine & bourbon are two I've seen great blind judging results from. Preconceived judgements affect final judgment, we're human after all.

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Oh yeah, I don't think the noise from a PC has a big impact on the sound since it's generally common mode and way out of band. However, I think it has more influence than a bit perfect stream coming from player A as opposed to player B. At least it's different.

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Dave,

Noise this, noise that etc etc. you haven't explained how that noise effect the USB noise when the DAC is not powered by USB power.

I think I am done.

Roscoe,

Thanks for the write-up on Sonore. So, its a device dedicated for Audio Streaming, therefore its firmware is analogous to RT OS.

So, it would be a very good comparison between Sonore and RT Linux (an any other streamers).
Jim, you are on.

Yeah, actually, he did. Noise can propagate through the common ground. Noise on the USB ground of the PC ends up in the USB ground of the DAC even if the DAC is not USB powered. The ground still needs to be connected for the signal to have a ground reference. Schiidt just came out with an updated USB board for most of their DACs that uses transformer isolation on the USB inputs to help deal with this problem, but this solution isn't widely used at this point...

Roscoe

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I can explain it to you, but I can’t understand it for you.

The second part of #2 is not correct. If the packet is not received at the receiving end in a USB transmission the sender is asked to re-transmit. See below from Wikipedia:

If a USB host does not receive a response (such as an ACK) for data it has transmitted, it does not know if the data was received or not; the data might have been lost in transit, or it might have been received but the handshake response was lost.
To solve this problem, the device keeps track of the type of DATAx packet it last accepted. If it receives another DATAx packet of the same type, it is acknowledged but ignored as a duplicate. Only a DATAx packet of the opposite type is actually received.
If the data is corrupted while transmitted or received, the CRC check fails. When this happens, the receiver does not generate an ACK, which makes the sender resend the packet


If there is only a small problem with the transmission the re-send will usually happen with enough time to prevent a dropout. If the problem is severe enough, the transmission will fail. Remember that USB is asynchronous so you don't have the problems with jitter like you do with SPDIF or AES/EBU that are synchronous. Instead of jitter noise you will have droupouts that if severe enough and repeated can sound like static.

Tom

I am not sure that is correct in all instances.

For example the xmos I am using is electrically isolated from USB. It is powered by DAC including the ground reference.

Even if the ground is common with the PC, it really doesn't matter in the digital domain for deciphering 0s and 1s and the there is a huge voltage range to represent 0s and 1s, the switchover point is far away from both the ground voltage (0v) and power supply voltage (+5v).

It only matters if and only if the xmos ground is connected to the DAC ground.

You've never looked at a PC ground on an o-scope, have you

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I can explain it to you, but I can’t understand it for you.