DAC connection: which type gives highest fidelity?


Suppose one wants to connect two digital devices, as in a streamer to an outboard DAC or similar.

Which is the highest fidelity connection?  USB, coaxial, or other?

Thanks!
bobbydd
@bobbydd

a word of caution to you

the dena dacs’ input card has issues receiving a hi res signal (above redbook) from the bluesound node/node 2i (pontus, ares 2, gaia)

it is the ONLY family of dacs that has input compatibility issues with the node digital out... and i have had 40+ dacs in my system since january 2020 (no exaggeration)

alvin says the digital signal output of the node is 'on the low side', and the input receiver of the gen 2 denafrips gear thus won’t recognize it (you get a bunch of subtle pops coming through the system as opposed to music when this happens) - alvin says ’just use the optical connection’

so be warned...
WOW my computer to DAC connection is schizophrenic. My older DAC does have USB, It's a CAL Alpha.  My newer Mini Mac does not have Toslink/Fiber.  I use a USB to Coax Adapter.  Sounds great if you considering the age of my gear.
I would suggest optical network-based raw data transfer (e.g. a UPnP renderer) as it has both error-detection and retransmit while also being electrically decoupled.

But, in practical terms, it pretty much depends on the implementation of your sender and receiver. For some devices, the USB input may be better than the coaxial one, while for others it will be the opposite.
Ethernet!    Data send in packets, ability to resend data if if errors, data integrity from IP layer, simpler implementation with  synchronized data transmission ...