I2S, S/PDIF, Toslink connections


In searching for a new DAC the input choices are many. There are several ways in which inputs can be connected to a DAC and this can be compounded when an USB/SPDIF converter is inserted between computer and DAC. I wish to learn more regarding the SQ as afforded by these inputs.

Specific questions:
I am of the understanding that coaxial is superior to toslink when connecting CDP to DAC. Is this true?

What is an I2S connection and what are advantages to this option? Uses an HDMI cable i believe.

Thanks in advance for helping with my understanding.
mesch
That's 2. Not as many as the original I2S and not standard HDMI either so that's a consideration.
Given that the system does not have significant ground-loop noise, the coax interface will outperform the Toslink, If you use a decent coax cable that is. The Optical conversions add jitter. If the system has a lot of ground-loop noise, the Toslink will be better simply because it breaks the ground loop.

I2S is the native interface to most D/A chips. Because there is no need to encode the clock and data into a single signal, this makes it superior technically to S/PDIF coax. Termination and handling of the transmission-lines of I2S is non-trivial however and many of the early implementations were not very good. I2S consists of 4 signal lines: MCLK, SDATA, L/RCLK and SCLK (aka BITCLK). The HDMI connector used with the differential version of I2S was chosen by PSAudio and adopted by Wyred 4 Sound and Empirical Audio, who also uses RJ-45. I2S has been used in single ended version with DIN and RJ-45 connectors for about 10 years. The earliest was Audio Alchemy. Differential version has 8 signal lines and ground. Single ended has 4 signal lines and 4 return lines (grounds).

Steve N.
Empirical Audio
I2S is also available on North Star as RJ-45, which I am using.
It certainly is the best connection.
I wish to thank all for their response. Are there no USB/SPDIF converters that output I2S to any of the aforementioned DACS?
Dunno but it is doable. I wrote a pair of articles many years back (1995-7) about how to do this. They appeared in Audio Amateur which has morphed into AudioXpress. The articles were called "Get on the Bus" parts 1 and 2. While the specific devices referred to are a bit dated, the general principles are the same.