OK, I have completed my tests for best connexion between my Aurender W20 and my Denafrips Terminator R2R DAC. - First I compared the 3 connections ( AES, Coax and USB) with 3 cables from the same manufacturer (HifiCables.fr) using the same topology/technology. Against all odds, the USB was the winner ! sound stage was wider than with coax nor AES. This is un-expected since Aurender recommend AES rather than USB (the result can be very different with another Source/DAC combinaison) - Then, since USB was apparently the best connection (for my set-up) I tested 3 different USB cables : the "Aucharm" a low cost very good Chineese cable (50$) that was highly recommended by a tube amp manufacturer friend of mine, the HifiCable's "Super Ultimate USB" (290 €), and a very expensive Synergetic research Galileo LE USB ( 2500 $) that use a separate transformer and other (marketing ??) gimics. Again, the results were quite surprising: I found that the HifiCable lacked some musicality (it was precise, but something was missing reducing the possibility to "get lost into the music") while the 2 others provided a very engaging experience and... I had a very hard time to differentiate them. I guess that with a HP system the difference will have been obvious but with headphone the 50€ is super close to the 2500€ cable ! this may be due because a « headphone » system do not offer the « spatial » criteria that can make the difference between a good cable and a very good cable. So, I returned the 2500 € cable and... kept the 50 € cable. So... I was quite disapointed by what was supposed to be a super-TOL USB cable... ! May be someone can suggest another Super-TOL USB cable that will really bring a substantial sound improvement over a good 50€ cable ? - next step: I will test soon the "Curious cable" and also I will have made for me a specific Coax cable to give the SPDIF Coax connection a second chance against USB.