Does the I2S conversion also apply to other inputs like SPDIF?
Previously I had a W4S DAC and Music Server. Out of curiosity I added an I2S output on the Music Server to use the I2S input on the DAC. E.J. at W4S told me the USB was a better input and I proved him correct. I am reluctant to install and add-on I2S board again.
When I had a Denafrips TP and Iris the I2S was the best input until I upgraded the firmware for the FPGA and USB receiver. After the upgrade I felt the USB was better than I2S, however there was a glitch with the I2S pin out settings not being able to play both PCM and DSD on one pin setting. I don't know if that would affect the SQ. I think the USB firmware upgrade made it better.
My W4S was optimized for USB, the Denafrips for I2S and it seems to me the Golden Gate for SPDIF.
Yes, quoting field experts: I²S is more or less the native interface of DAC chips. The reason it can sound "better" is that it isn't modulated like SPIDF, thus keeping the clock and data signals discrete, which creates the potential for lower jitter figures. However, I²S is not a standard for transmitting data, as it has no specs for data and connections, the reason we see so many different implementations (various hdmi or ethernet configurations).
That said, USB or other conversion methods to I²S can sound just as good, but there is always a certain "duality" in the nature of their implementation, as both the transmitting and receiving (server and DAC) ends have to be on a par as far as implementation is concerned and possibly also why we see so many different SQ differences. This "duality" can of course extend to I²S to I²S implementations as well.
So indeed, different equipment with different "dual" implementations, can yield different results and as audiophiles we can only go so far as to try and see which combination ticks most of the boxes according to our systems and preferences.
My take on the matter (per post #34 above), and the way I try to approach it is this: I also currently use USB out (from the Pulsar through the JLSounds board in my Lampi) and have no regrets regarding SQ, while in the future, I aspire to move to an I²S to I²S configuration, hoping that -ceteris paribus- the elimination of an extra conversion stage will work beneficially towards a SQ increase. Let's see what tomorrow brings...