SP/DIF or USB

[Clive197]

I have been experiencing a very small but annoying issue with the connection between my Aries G1 and my Qutest, using SP/DIF to the BNC input on the Qutest. I have been experiencing a slight drop-out when listening from my NAS or a streaming service which is mainly Qobuz. The drop-out is not much more than a scratch on a record and will generally only happen once after a couple of hours. After 18 months of this and because I’m getting a little stir crazy after nearly 3 months of lockdown I decided to investigate.
Reading the manuals and looking online I’ve discovered that both units really prefer to be connected by USB. I have always been of the understanding that this was an inferior connection but hay lets try it.
I pulled out a Atlas Element (s) USB cable that I was given when I bought the Aries and replaced the digital interconnect with said USB. Result, no more drop-outs over the next 5 days and the added benefit of an improvement in frequency extension and sound-stage. Who would have believed it. I thought further experiment was called for, so I purchased via eBay at a very good price a Chord Signature Tuned Aray USB cable. Comparing this with the Atlas over the next 5days I came across my usual impression that there was little difference between the two digital USB cables. I have always heard differences between analog connections but struggle with digital.
There was certainly a difference between SP/DIF & USB which I believe to be down to the electronics and not between the cables.

So without trying to start world war 3, I wondered if any of you had thoughts on this. Please don’t start a cable discussion but I’m interested in thoughts on the SP/DIF vers USB issue.

[doodoos]

I think it depends on the hardware at each end of the cable. I also use the Aries with coax into the dac and it sounds fine. usb is too much of a pain for me but I’m told is the better connection if using a pc as source.

[Mand]

Another G1 user with Schiit dac. Tried both usb and spdif..
Different presentation of staging, usb wider and airier. Slight difference in bass, could live with either.
Long term listening is nicer with usb - somehow more at ease but then sometimes too at ease.
So I have both connected and swop now and again.

[Qwin]

I was always wary of USB, it used to get a bad press. Much of that relates to USB having lots of unrelated traffic on the line, I think that might be less of an issue on a dedicated streamer. I used USB recently to connect a RPi4B to a Topping D90 DAC with very good results.

Okto Research use Asynchronous USB for linking their built in Pi4B and DAC boards on the DAC8 Stereo, the inverted Pi plugs directly into their PCB header, using the Pi's GPIO socket, so no cable involved.

With USB you can use DSD native if your hardware supports it, you can't do that with SPDIF if I'm understanding that correctly.

They use different methods for transmitting the data.
SPIDIF is a single wire/Stream of data so the Clock Info/Data etc has to be broken into chunks and sent in alternate bursts down the line, which is reassembled at the other end.
USB is multi Wire/Stream so each form of information has its own dedicated wire/stream and all the information is sent simultaneously.

I don't know enough about the technologies to comment on the merits of each system but as I understand things, that's the most basic difference.

I've had good results using both and suspect implementation is more important than which method.