DAC connection: which type gives highest fidelity?

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 ...

bobbydd OP
DAC connection: which type gives highest fidelity?

The very best was/is?
If you have the optical AT&T bnc type high speed optical glass fibre connector’s that Wadia and ML’s some used in their top models, these are the best, and you use them with a dab on the ends of the expensive "optical indexing fluid" that gives them an air free mating connection. The glass fibre lead is very fragile and can't be bent too much as the glass fibre cracks.

Cheers George

This is from the Pontus 2 spec list on the Denafrips page. I have no reason to doubt what Alvin passed on to jjSS49, so beware there.
DSD
DSD64 (DoP) on Coax/AES/Opt Input  
DSD1024* On USB & I²S Input Only
PCM
24bits / 44.1, 48, 88.2, 96, 176.4, 192KHz On All Input  
1536kHz* On USB & I²S Input

Clearly, Denafrips has put a great deal of effort into their USB and I2S inputs as they probably reasonably expect those to be the most commonly used.

As have Antipodes with the USB output on their line of server/streamers of which I'm a very happy owner.

I have the S30 and use Roon with a Curious Cables USB cable into my Pontus and it sounds fantastic to me when streaming Redbook and higher.

I'm considering trying one of the Denafrips reclockers to use the I2s input as their DACs respond very positively to that input by all accounts.

Just curious about the Node/Denafrips issues. I feed my Denafrips Ares II via the Node (2021) using only digital RCA coax. I listen to Tidal and Qobuz at all bit and sampling rates available; I’ve never witnessed this at all to be honest.

I’ve seen this issue documented here and on other forums, but maybe the issue was resolved with newer generation of Node products? Or am I just lucky? 🍀