Which sounds better: I2S or Coax.

The quality of the components and implementation is everything. Early versions on a new connection standard is something to be considered as a requirement years after it becomes a standard. So, for today I would concentrate on the sound quality of the component… and use the best connectors available… AES or SP/DIFF.

If the DAC is designed properly, the interface will make no difference. I2S is another way to extract coin from your pocket.

Hi RSA -

If you will be using PS Audio, you can only use I2S if you wish to access everything  that the PSA transport & DAC will offer. Period. End of Story.  This is how PSA designed its components to work.

The SACD handshake will only occur properly using I2S, assuming SACD playback is important to you. Be aware that not all I2S (HDMI) cables are created equal. Also, you will need HDMI, as opposed to HDMI 2 cables.

Follow these rules and you will be rewarded with some very nice equipment and sound. I have the Stellar Gain DAC & Perfect Wave SACD Transport talking to a Rogue Sphinx integrated and Zu Audio Omen bookshelf speakers. I am using an Audioquest HDMI cable. Check out the PSA Forums. Lots of threads on the subject.

Rich

My understanding of I2S especially for SACD playback is there is no industry standard hence some manufactures of I2S capable DACs built in some configurability of their I2S pinouts (in this case, I think HDMI).  SACD DSD playback with I2S seems so complicated unless the DAC is from the same manufacturer as the SACD player ?  I've asked Paul McGowan of PSAudio to do a video on this very topic for years now but has not materialized.  Perhaps someday...  

I do not know how well I2S works with PCM.

Correct.  There is no industry standard, so it is proprietary to the manufacturer.  In the case of PSA, its SACD transport is designed to work with its DAC using I2S (HDMI).  That is just how it is.  

When I first purchased the PSA SACD transport I was not using a PSA DAC.  I thought any DAC with an I2S connection should work.  Not to be.  I the purchased a used, 10 years old PSA DAC.  Not to be Part 2, as the new SACD transport is not backwards compatible with the 1st (?) generation DACS.  

Great support from PSA every step of the way.  Paul spent many weekend hours with me diagnosing what was going on.  At the end of the day, PSA offered me a tremendous deal on a new DAC.  So, all is well and I am extremely satisfied with PSA and my set-up.

Keep in mind though, this is how PSA has designed its SACD handshake.  As a side note, I do believe there is an 'Ask Paul' YouTube video out there on I2S.

Rich