Why a new dedicated SACD player has more noticeable sound quality difference than HDMI-I2S with new external DACs?

[Killingbeans]

You could just connect with s/pdif (coax/toslink) instead. Cheaper, neater and no audible difference.

 

[Roland68]

Roland68, what are good sources to buy HDMI to I2S converter ?

I bought a simple board for my own wiring. Only HDMI input and a pin header with I2S and SPDIF output, nothing more.
HDMI Extracts Digital Audio Signal I2S
You will then need a cheap board with I2S input and I2S over LVDS (HDMI) output and a clean 5 volt supply. The wiring between the two boards should be as short as possible, under 10cm.

 

[Kiko1974]

Just in case this helps: my digital set up is a Sony UBP X-8OO M2 UHD BD player, that also plays SACD's and DVD-A's, the external box shown Here, that takes HDMI audio from HDMI audio port (labeled HDMI 2) from the Sony player, and outputs DSD as I²S and also as DoP.
The Sony UBP X-8OO M2 doesn't supply enough current to get the HDMI to I²S box, so at first I used an 15 Euros power supply.
The sound was so so.
I then changed the inexpensive power supply to a better quality LINEAR POWER SUPPLY.
Since then sound changed for the better, the SMSL D 400 PRO DAC I own sounds like a charm since the introduction of the Linear power supply.

 

[antcollinet]

I am asking whether it was jitter or something that I don't yet know , not stating it was jitter.
There are a few of us (me and friends who owns respective gears) who confirmed the observation stated above.

The HDMI to I2S is an external box , we got from eBay such as this one https://www.ebay.com/itm/314981678249?itmmeta=01J40948BM8BPTM3Z21XJHBQZM&hash=item49565efca9:g:MGYAAOSwOW9lXvCp&itmprp=enc:AQAJAAAA4H9ND85T1GiiUy/mU6lnYqczjNaSMyW0iquc9P+wjw67j0HCW6jX7ZbKTrklEsaV70rH5lfM8esIUpwBUQaO3fhx0zjZUpbUhh7MURQBMCyfIjK1PeYrowXv7lRthuRdc0X3BeScUeM3WbY6ZswEzeJ+4KpRg1ciWd9YRslSCZVE41hu0hb02aM0k5PPX8DO5ah8FXhxEH3qSNAjRvPt0AcoLD7YG+/Esc1D0CJWwrsc4eeydq0mLxKjrjtYacUMeMu7T5MC2g+6NRlE9/h8grigt7EV47IKH/Wq/vbrfiff|tkp:BFBM9oWRiaBk

As pointed out above - there is no point asking such questions unless the tests are properly controlled (Accurately level matched using a multimeter - an SPL meter is not accurate enough - and blind - ideally double blind, but at least with no communication (verbal or non verbal) between the participants about what they are hearing.

Otherwise there is no way of knowing if the differences perceived are really in the sound or are being created in the listeners auditory system as a result of perceptive biases - or just insufficiently matched levels. These things can create very real sounding perceived "night and day" differences that simply don't exist in the sound waves reaching the listeners ears. You say "we know what we heard", but without proper controls, you literally do not.

Important note - I am not saying there were no audible differences (though the overwhelmingly most likely case (if the masters are the same) is that there are not), but I am saying that without either controlled listening, or measurements it is not possible to know.

Asking "is it jitter or something else" is moot unless there is valid confirmation that "it" exists at all.