Why does USB feature so much in discussions about DACs when the newer HDMI seems better?

@sns HDMI natively supports pure audio - have a look at my earlier post where I list what it can do.  It is a very impressive list, certainly way beyond I2S.

Now, HDMI connectors are attractive for other uses.  I have a camera system in my motorhome which supports four analogue TV cameras feeding a single display. Dometic, who makes this system, choose to use HDMI connectors to carry the analogue TV signals.  Despite there being a standard HDMI connector for in-vehicle use, Dometic use the totally unsuitable consumer connector!  Hopeless.

I had never heard of I2S when I started this thread, but I can understand how HDMI with its 19 connection pins would provide an easily available way to transmit four signals.  But it certainly is not native HDMI.  There are 10s of billions of HDMI connectors in the world today.

@devinplombier I am equally staggered! 

You did not mention the latest incarnation of USB which has a connection count of 24 wires!  The connection topography is shared with several other technologies including Thunderbolt!

The naming and description of this latest USB evolution (revolution?) is confusing in the extreme.

My understanding is that for use of the latest features, the cable itself needs to be active.  That is, it has to have embedded logic chips.  That's how it can carry HDMI, which itself can carry Ethernet.

@mikhailark Absolutely spot on!  On another forum, an audiophile claimed there could be no difference audible between CAT5 and CAT6 Ethernet cabling, because audio frequencies are much lower than Ethernet transmission rates.  Anyone who does not get the point, does not understand how audio is carried over packet switched networks.

By the way, Ethernet on its own does not guarantee that a packet will actually be delivered, nor does it guarantee how long it may take to transmit a packet.  To probe why, take a trip to the Hawaiian Islands and try to understand the ALOHA radio data system which was the genesis of Ethernet.  The secret is in the CSMA/CD acronym - Carrier Sense, Multiple Access / Collision Detection.

The internet is also packet switched technology, which is evolving mainly through Requests For Comment!  Audio over IP (Internet Protocol) uses packetisation, whatever the physical wire arranement.

SNS

You've nailed it perfectly. There are SO many reasons to use I2S if you can, and you explained it really well. I agree that short HDMI cables are best, but I've had excellent results with the Audioquest Vodka 48 8k/10k cable at 1 meter. For small budgets, the Supra 2.1 HDMI works really well as does the Audioquest Cinammon HDMI.....but those needed to be shorter than 1 meter for best results

It is true that there is no standard for I2S pinouts, but I've never had a problem with Supra or Audioquest. Also many DACS provide pinout configuration, I know that Denafrips does in all of their DACS.

The other benefits can be true of DDCs too, as it allows for: better quality clocks, galvanic isolation, optical isolation, separating the data and clock signals, and of course keeping the I2S signal in tact from the DDC through the DAC.....with no further conversion until the Digital to analog conversion in the DAC

@sns, @vthokie83

Good explanation of USB versus I2S, but nothing about the native audio capabilities of HDMI!  Remember, HDMI handles multiple audio channels at breathtaking rates and these days includes an Ethernet channel to boot.

I am starting to question why audiophiles don't advocate for mono over 2-channel stereo.  How many backward steps can be taken?

richardbrand

That's true, I did not....and I do understand your point. I'm not an electrical engineer (I'm mechanical) nor a builder of audiophile equipment. I was responding to the various USB/I2S/SPDIF/Toslink posts in between, and reflecting on my own personal experience with my system