Why a dedicated SACD player more noticeable sound quality difference than HDMI-I2S w/ DACs

Who is “we”?

Yes!

Me and my friends who brings audio gears to run this experiment at friend’s house who has the best acoustically treated room.

I have an Oppo 105 not currently in use. If I’m not mistaken the fidelity is reduced using hdmi due to licensing. Does that come into play for your experiment? There’s a product to solve that , I believe it’s called The Break Out Box. Cheers , Mike. 

You used a cheap Oppo which is inferior to the much better SACD players out there.  Not a great comparison.  

Agree Oppo 105 is not the best SACD Player.

My observation is about the lack of sonic differences in External DAC vs a new dedicated player, so was curious why?

While I love science and comparisons… but, you guys have way too many variables and are comparing consumer grade front ends on DACs in different leagues. 
 

One thing… like connection type and the input mechanisms should be closer in resolution and quality to the amp / speakers. 

I Donot agree with that.

if you properly remove weak links in your digital chain ,and provide Quality 

Digital is best in many areas. In our large  audio group I have see. Most everything 

out there.  From you router that cheap noisy wall wart ,get rid of ,replace with much lower noise LPS ,linear tube audio makes a great one 

quality Ethernet hub at minimum $600 LHY  SW8: if you can afford better $3k substantial improvement Danish Audio group, or Innuos, quality Ethernet cables 

put best one at end point ,and a quality streamer with a LPS ,Dac needs to be at minimum $2k on up . Then you will hear a substantial Digital experience quality power cords also a must .

My statement is not about A is better than B.

Our observation is that a dedicated new SACD player has more audible sonic differences than simply adding different external DAC (in this case thru HDMI-I2S adapter) to existing SACD player.

So was curious whether anyone has observed the same or have knowledge as to why that is.

I just replaced an OPPO 103d I was using as a "transport" with a dedicated transport , the Teac VRDS 701t .  Night and day difference,  no comparison. 

Wish I had done this a long time ago.  The difference is not subtle , the OPPO was poor as a music transport.