I am re-evaluating my thinking on upstream sources with the NS1 (with Optimism cable)+DA2 v2. I'm curious if others have found some improvements upstream of the NS1, or in place of the NS1.
Last year when I received my NS1 I compared using my Innous Zenith MKIII as a server via Shunyata Sigma ethernet cable, with just attaching a USB hard drive to the NS1, and the USB drive won by a hair. If memory serves, I also tried inserting Uptone Etherregen and LPS 1.2 between the Innous and NS1, and it actually sounded worse. It's almost not worth mentioning that the NS1 was better than Zenith+Phoenix into the DA2 USB. I concluded that the USB hard drive was the best I could do and that a dedicated server was of no use because of the optical isolation.
Recently, I actually tried adding some iFi USB isolators (iGalvanic 3.0 and iPurifier 3) I had laying around, plus my Shunyata Sigma USBS and some Q45T between my Seagate USB hard drive and NS1. Lo and behold, more detail, contrast, dynamics, and less noise. My thinking is that any USB or ethernet input to the NS1 does have the ability to inject clock noise into the streamer, and electrical noise into the power system (esp through the USB 5v power wire).
The only downside of my setup is a slight artificial sheen that I'm guessing comes from the iFi reclockers. Now I am interested if there are even better ways to clean up the electrical noise and clocking upstream of the NS1, whether network or USB.
I never tried a NS1 so I can’t comment upon it. For a streamer I chose the Aurender N30SA. The N20 would get you really close to the N30 and costs less. It integrates wonderfully with the DA2V2 DAC.