Server to DAC connection

I agree with Lalitk, that spdif is superior sounding to usb. At least, a few years ago when I did a/b testing with my own gear.
l'm not familiar with your equipment, but I own a music server that is usb only, and a DAC that can accept various inputs including usb. I went with an Audiophelio usb to spdif converter, and this dramatically bettered the straight usb to usb connection in every musical sense.
In your case, you can do spdif to spdif, so less may be more, unless there is real magic in the Berkeley.
I'm not sure if this helps you, but wanted to share my experience, because my Audiophileo does work magic in my situation. Did Hartley explain his opinion on why the Berkeley improved things? For example, it further reduced jitter thus sounding better than Aurender's straight spdif output?

lalitk,
I did briefly compare the M2-tech HiFace Evo to SPDIF, and I preferred the M2-tech. However in the process of fiddling with the M2-tech, I  damaged it. It is not a robustly made unit. My understanding is that the Berkeley is even better than the M2-tech.

KTK,
I don't think Harley explained the reason he preferred the Berkeley converter to AES or SPDIF. But, I suspect its related to the reduction of jitter and the re-clocking that occurs in the Berkeley.

Based on the above responses, one could surmise that direct SPDIF beats direct USB, but USB converter (Berkeley or M2-tech) beats them both.

You're making way too much of Harley's statement.  I just don't think you can generalize about what connection is better across different systems with different digital components.  The exact implementation of the interfaces can easily override any theoretical considerations.  If you setup allows multiple signal paths, then take the time to try each one and determine which one you prefer.

psag,  

IMO, N10 does a great job of minimizing digital noise and jitter control.  If you do end up up trying Alpha USB, please post your finding here.

Here's to another tweak and relentless pursuit for audio nirvana 🍻