Digital Cables

Per Chat GPT: 

Why the Node N130 USB does not work with the IRIS

1. USB role mismatch

Node N130 = USB host that outputs audio only to USB DACs

Denafrips IRIS = USB device that expects a computer/streamer acting as a USB audio source

The Node’s USB stack is restricted:

It does not output generic USB audio streams

It only supports DAC-class devices, not DDCs, reclockers, or format converters

2. Real-world confirmation

This isn’t theoretical:

Multiple users have tested Node → IRIS (and Node → Gaia)

The IRIS does not appear in BluOS as an output option

Denafrips themselves do not list Bluesound Node as a compatible USB source for IRIS

So your current plan — Node → coax → IRIS → I²S → Pontus II — is exactly the correct workaround.

Practical reassurance (important)

You’re not missing out the way it might seem:

The IRIS reclocking + I²S stage does the heavy lifting

Coax from the Node is not the bottleneck once the IRIS takes over

Many Pontus II owners run this exact chain very happily

If you want, next we can:

Compare Node → IRIS vs a true USB streamer → IRIS

Or talk about which streamers do output USB audio to DDCs around your budget

@maprik There seems to be a philosophical difference between manufacturers of digital gear between USB and I²S as the connection of choice.  Either is (usually) better than Coax, TOSLink or AES/EBU - though Aurender recommend their Coax for some streamers.

Your IRIS box tidies up the S/PDIF, reclocks it and outputs the I²S streams (data, bit clock and word clock), the DAC then uses the clock signal from the IRIS, which has been transported over the HDMI cable,  Hence the critical nature of the cable.

Esoteric use a proprietary current based flavor of I²S, ES-Link, for their Grandioso separates.  At $100k or so.  I guess that they decided that the best bang for the buck in the $15k to $30k range was asynchronous USB with a precision clock and a FIFO buffer.

There are (heated) discussions of the merits and problems with USB and I²S on this Roon forum https://community.roonlabs.com/t/usb-and-i2s-which-is-better-for-connecting-dacs/274372/8

Denafrips have chosen I²S as their "flagship" interconnection, and, yes, the cable quality is critical. The routing of that cable may matter also as it should be away from EMI noise. 

This is the sort of discussion that helps to make the equipment side of this hobby fun!

maprik

I use USB for sure, and have been since March/April of 2023. The Node 130 model that I have was the first BlueSound to actually use the USB for output, up to that model (Node, Node 2, Node 2i) it was for storage only......not data transmission.

I assure you that it works on the Node 130 and newer models.....despite what ChatGPT says. Also the USB from Node 130 to the Iris works better than whichever SPDIF connection that you use.

retiredaudioguy I got out of that fight a year or so ago, I use what sounds best to me. I also understand that when I do upgrade my streamer and DAC next year, I'll have to rethink the whole connection issue.

Different companies choose to optimize different connections, one may optimize USB, another AES/EBU, another I2S. I also notice that more high end companies are adopting I2S, it no longer appears to the restricted to ChiFi gear.

Maprik

I just re-read my post, the second paragraph I incorrectly said "Iris"; it should have been "Hermes" which I've also tested in my system.

@vthokie83 Omg. So I should be looking for a high Quality USB cable from my Node N130 to the Iris!!???