I2S was designed for audio. Toslink was a cheap way to send digital signals developed by Toshiba. USB was for data not audio. When you look at it from a cost and convenience factor and take into consideration what technology was available at the time, one can see higher end audio components are using I2S because it’s better engineering and better sound today. Of course anyone is free to use whatever connector that might have and if it sounds fine for them…. no worries. Paul McGowan of PS Audio explains these differences pretty well in his informative YouTube videos.
Why does USB feature so much in discussions about DACs when the newer HDMI seems better?
I am a bit confused about the frequent mention of USB in the context of stand-alone Digital to Analog Converters (DAC). Why is HDMI left out? Is this a US versus Europe / Asia thing?
The Universal Serial Bus (USB) was introduced in 1996 by a group of computer manufacturers primarily to support plug-and-play for peripherals like keyboards and printers. It has only two signal wires, plus two wires that can supply DC power.
The High-Definition Multimedia Interface (HDMI) was specifically designed by a group of television manufacturers for transmitting digital audio and video in many formats. It hit the shops around 2004. There are 19 pins supporting four shielded twisted pairs, and seven other wires (3 of which can instead form a shielded twisted pair for Ethernet).
I have three universal disk players from Sony, Panasonic and Reavon, which all have two HDMI outputs, one can be dedicated to audio only, the other carries video or video plus audio. (Only the Panasonic does not support SACD). My Marantz AV 8802 pre-processor has 11 HDMI connections and only two USBs.
Of course, both USB and HDMI continue to evolve. Then there is the Media-Oriented System Transport (MOST) bus designed by the automotive industry, which looks even better.
Why is it so?
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My take: Audio Video HDMI is only available within the video world. BluRay players that can play SACDs works only with Home Theater receivers that can decode DSD. I only have experience with SAME BRANDED BluRay and HT Receivers. Not sure how well it works with mixing brands. To make it more confusing, then there are SACD players that use HDMI (that is I2S, but uses HDMI cables, no video involved) that can be connected to external DSD capable DAC using I2S via HDMI cable. It can be a bit complicated as I2S pin outs are NOT standardized. So caveat emptor |
I used to stream from my Mac mini using the headphone out into an adapter for optical. But your limited to 96khz 24 bit. With an external streamer/dac like auralic, you can stream much higher resolution with less noise from a computer. 192khz/24bit and 512 dsd. No usb connection, all Ethernet for streaming or wireless and balanced output. |
@emergingsoul maybe this. I have one I’ve used just for digital audio output and worked well.
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@richardbrand - can't say for sure, but I'd guess that most people who stream do it from their phones.... |
All of my recently purchased silver disk spinners support two HDMI connections, from the very cheap Sony transport (A$250 or so) and up, I guess for exactly this reason. In my case, the lauded Texas Instruments Burr Brown DACs in my Reavon player turned out to be far worse than the eight 2-channel AKM DACs in my AV pre-processor. I would encourage you to read the specification sheets of any DAC chipset you are considering. For me, it is very important that they natively support Direct Stream Digital (DSD) which I guess rules out R2R. If the specification sheet does not mention DSD, you can bet your top dollar the DAC does not support DSD. I note in passing that DSD can be mathematically converted to multi-bit without interpolation, but multi-bit needs interpolation (guesses) to go the other way. |
I would like to find an HDMI splitter, that I can use to feed audio into my dac and have the simultaneous video be fed into my av processor. I’d like to be able to bypass the dac in my processor and maybe I can get it to sound better. Although, maybe it won’t sound better because my processor is very good. Would love the flexibility to pursue other dac options.
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@daveteauk I guess so....I was going off the P-Link glass optical cable that Playback Designs uses to connect their streamer to their DAC. That cannot be beat by any cable. |
@vinylshadow - Toslink, whether glass or some kind of plastic, is THE worst thing to use for audio connections. It's been slagged off for decades, since it was first used for audio in fact, for having terrible sound quality. Obviously opinions will vary, but it totally depends of the resolution of the system - if you have a poor/low quality system, it probably sounds OK. |
It depends on the manufacturer in my experience. I have a Holo Audio Cyan 2 DAC. It has multiple inputs. Holo makes a Red streamer which connects through i2S which is tailored to connect between the two units. I didn’t like the Red and the apps I needed to use. I went with a Innuos Zen Mk3 streamer instead which only connects using USB. It sounds excellent in my system. Would i2S sound better- possibly if I could even tell the difference with my old guy ears. I love the Sense app that Innuos uses, even better than the BluOs app which was my previous favorite. I only use HDMI connections with my TVs. So many connections and so many different cables. Pick what sounds good to you in your system. |
USB is a terrible interface to a dac. Ethernet is better and i2s is even better. Most won’t know this because they buy cheap stuff and the cheaper stuff doesn’t include Ethernet or i2s. For a decade, all your high end manufacturers provided a proprietary link from their space player into their preamp or integrated or possibly a dac. They used hdmi/i2s for this. I use a streamer that doesn’t even include usb out, only i2s into my dac |
The best connection is the one supported both by the streamer and by the DAC. Some manufacturers have their own connections (like Auralic’s Lightning Link) or use I2S, and many say that the sound is best if those are used. I have no experience with that. Leaving aside specialty links, if USB is available, I like to use that, as it supports the widest range of sampling rates. Also, over USB, the DAC controls the clock entirely, without depending on the source. I will say, though, that with the new equipment I’ve tried recently, I cannot hear any difference between USB and SPDIF or AES3. |
Yes, that makes sense for computers. My partner's Dell XPS 13 has so little space for any physical connections, it has an external adapter to support HDMI and Ethernet over USB! What about separate streaming boxes. What would be the best connection to a DAC for them? Do most people stream via computers these days? The only streaming I use is to check the music out before buying a disk, and I use WiFi (great Australian invention) to connect my mobile to the pre-processor for that. |
Most computers have several USB ports, so one is likely to be available for digital audio output. On the other hand, not all computers have HDMI, and the ones I have seen have only one HDMI port, intended for the monitor. All that makes USB a useful input for a DAC. Of course, some newer DACs are adding HDMI input. |