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USB vs Coax Is one better than the other?

I am wanting to buy a cable to go from Auralic Aries to a RME adi2 dac with a Teddy Pardo psu. I am using the stock USB that came with RME and a JPS Labs Superconductor digital cable I had lying around since 1997 it's the first generation from JPS. I can pan between the USB and Coax with streamer remote and find there is a difference in sound, not sure if it is the signature of JPS or it being a coax wire vs USB. The USB sounds more detailed and clean. Coax more analog and full. Both are enjoyable but just different. Should I invest in USB or Coax, thank you for your advise as I'm a little lost here.
paulcreed
djones51
4,947 posts
 
Before you decide anything are you level checking with a SPL meter when you switch between coax and USB? We tend to favor the louder sound at least short term so even if you just download a SPL app and try to get the sound level close at your listening position you're not giving yourself an accurate assessment of the two. 
thyname's avatar
thyname
3,107 posts
 
I agree with Dow Jones. Level matching is very important when doing comparisons. 

Also, from my experience only, take it for what's worth, USB cables tend to differ much more than the coaxial digital cables. In other words, upgrading a USB cable may give you more overall gains than upgrading a coaxial cable. 
antigrunge2
1,398 posts
 
This all,depends on your Dac‘s inputs. Many still have mediocre USB implementations whereas S/PDIF is established and seems easier to get right. Big issues on USB tend to be galvanic insulation and managing EFI/RMI. Conversely USB tends to allow for DSD and higher PCM sampling rates which Coax can‘t accomodate. It‘s not just the cable, I am afraid...
paulcreed OP
556 posts
 
Thanks for advise, I did check with a SPL meter and had to back down 3 notches on a 100 step preamp with the coax wire to match USB before I posted. I like that USB sample rate is higher but I do find some high-rez is not always the best in my system, can sound a little compressed. Is reason Coax sounds more natural because sample rate is lower? This is very confusing how to pick a type of cable, I'm still lost! 
mlsstl
1,433 posts
 
Rather than pinning all of the differences only on the USB cable vs the SPDIF one, which are passive components, keep in mind that we also have two substantially different active circuits involved, as antigrunge2 has already noted.

I'd give it good odds that the more natural sound you're hearing from coax may in your case be due to nothing more than it is a better circuit and more suited to quality audio than your USB option. (And, keep in mind, there is sending circuitry at the Aries end and receiving circuitry at the RME end, so even there the "blame" could be only in the USB circuitry at one end of the chain, or alternatively, the interaction of both ends.)

However, to me it doesn't seem to be a hard decision to go with the better sounding one.
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