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?