Best Digital Interface

Hi mofojo,

1. These two statements in the manual are consistent:

With USB the internal clock is used, with SPDIF the external one

and

Jitter suppression of external clocks: > 50 dB (2.4 kHz)

Jitter suppression of external clocks does not mean the DAC is reclocking the SPDIF signal, just that it’s suppressing some of the jitter. But like your manual and you have said, the Node 2 is running the timing show in this case. I think you’re right to think about reclocking, but I think you might be better served by running a SPDIF reclocker rather than USB reclocker.

2. I will disagree with you about Asynchronous USB being the "best interface for digital transfer to a USB DAC." Sure, Async USB is better than SPDIF with no reclocking. But, for now, I fit into the camp that says USB suffers from more jitter than SPDIF coax.

My understanding is that Async USB was designed for the "computer audio" era, when people would run their home computers directly into DAC’s. I believe that the main reason some people continue to use USB at the high end is because of USB’s ability to play large file types like 32bit PCM and DSD. I would suggest that we have now moved from the computer audio era to the streaming era, where most people are running 24/192 and lower only.

Although SPDIF coax introduces less jitter than USB, many SPDIF streamers need help. I think many members on this forum think too highly of their Bluesound Nodes and think too highly of their DAC’s capabilities. Why would you want a reclocker for every input in your DAC? That would greatly inflate the cost of the DAC, right? It seems to me like a better practice would be to build the reclocker into the streamer, or to place a separate reclocker between the streamer and the DAC.

On his YouTube channel, John Darko states that the Raspberry Pi with SPDIF DigiOne Signature reclocking hat outperforms the Node (~$500) and Volumio Primo (~$900) streamers. To demystify the Primo, it’s just an Asus Tinker Board inside. If you run any off-the-shelf board by itself (Pi or Tinker Board) directly into a DAC, it can only sound so good. These streaming boards are noisy little computers, and they need help. Not all streaming boards are equally noisy, not all master clocks are of equal quality, and not all DACs are of equal quality. More manufacturers are putting out master clocks now. Look into some. Just like you're bypassing the DAC in the Node with an external DAC, think about bypassing the reclocker in your DAC, which is limited to the USB input. It's probably not the best quality anyway. But it's something for people who use that DAC with a computer. 

I think you’re right, that if you ran a USB from a computer into your Async DAC, that may actually sound better than running SPDIF out from your Node with no reclocking. I would suggest that you try adding a reclocker into your current chain. You may be pleasantly surprised at the improvement. iFi and Wyred4Sound make the most affordable reclockers that I know of. Maybe start there. I use an iFi. On the What’s Best Forum, some members there report benefits running two reclockers in their systems. I haven’t tried that, but it’s an interesting idea.

Thanks classdstreamer,

I actually am running the IFI spdif reclocker currently. Not positive it makes an improvement for the node but am 100% positive it helps with the fire stick audio when watching tv. 

@classdstreamer,
Good comments, so the DAC is not actually reclocking SPDIF, only suppressing jitter. That’s a pretty vague statement.
Like you, I’m using an iFi to reclock the stream from my Node2i and the improvement is audible. I recommend adding a LPS.
Even with advancements in jitter reduction, I want the master clock at the destination and not at the source.
Thanks for the comprehensive explanation.

Thank you auxinput for some reality. For audio, USB connections are only required if you are using a computer as a music source. In order to use USB data for music it has to be converted into a data stream and clocked. A DAC with a USB input will do this for you. If you do not have a DAC with a USB input then you will require a USB to SDIF converter. I use the Berkley Alpha USB for this. There are various ways to transfer SPDIF streams, they are RCA by 75 Ohm Coax, AES/EBU by balanced 110 ohm cable, BNC by 75 Ohm Coax and finally optical by fiberoptic cable. There is no sonic difference between these formats. It is not music being transferred, it is clocked data, numbers. You do not have music until after the DAC. As for USB being "flawed" ? That is a ridiculous notion. USB does what it is supposed to do wonderfully well. It can transfer data packets much faster then one requires for music data. It is so fast a computer can transfer an entire 10 minute 24/192  song in about 10 seconds. A 10 minute 16/44.1 song would take less than a second.  
Digital audio devices do not need to use a USB connection because they are transferring the data already clocked in real time like playing a record.
They can music data between them in the digital audio formats mentioned above plus HDMI. 
There is no Coax to USB adapter because they carry entirely different signals. There are many sub $1000 streamers that have USB connections. They are called Laptop computers.

I suspect that "Best Digital Interface" and "Best Digital Performance" are apples to oranges.  While we can compare which digital interface is theoretically better, it's the execution in the component that sonically matters.  For instance, for some DACs the USB output sounds best while other DACs....