Digital XLR vs Digital RCA

"How good it sounds depends on my seats..."

Mr. dannad, if your home sound system sounds better than live, with RC, SACD etc’., you need to find better seats!

Digital interface:
The cable shall not be an issue, if the DAC section of the receiving unit is implemented properly.
The most common issue with Digital interface is Jitter. To prevent jitter a PLL is implemented over the input device, to synchronize clock and data within an accuracy of less than 50p Sec.Most PLL devices of the last 10 years would do (unless poorly implemented).
If you have an appropriate PLL, the digital cable should have no impact on sound quality.
As most digital Audio interface is PCM, implemented by SPDIF interface,
a single line carries both clock and data on  a bi-phase method.
The two are separated and the clock must be synchronized with the data.
For that sake, CD players with analog output were a better option over separate transport - DAC solutions, till PLL were good enough to go below noticeable jitter issues. 

There is nothing wrong with the engineering approach. Alchemy was long abandoned and science had prevailed.
The understanding of what is going on in a digital cable is better than ignorance.
The so called digital cable is not a mystery. It was actually designed by engineers, from PHILIPS Netherland and SONY Japan in the late 70’s.
This is why it is called SPDIF (Sony Philips Digital Interface):
https://en.wikipedia.org/wiki/S/PDIF
I love the silver over copper say, that is even better than snake oil.
The element silver conducts better electricity by 5% over copper but costs 131 times more. 5% in conductivity can be compensated with 5% additional cross section of copper. it may cost 5% more, rather than 131 times (13,100%) more. Be my guest and go for it. You may also throw that amount of $$ into the toilet and flash it down. You will earn the very same feeling.
On your fantastic hearing, we had some fantastic examples over medieval ages and later, when it was enough that two sister came out, saying they dreamed you are a witch, to burn you alive. Hearing the difference, is way more easy and no consequences, but drain your wallet dry. You can claim whatever you want, even if it is unmeasurable?
At age over 60! When did you tested last your hearing?
Up’s sorry! it;s tested by an engineered instrument. Not by a doctor’s or nurse hearing to compare with. Go get your glasses that way...
The human ear was never nominated as an instrument. Hearing is individual. The best part of "I can hear the difference" is that no one can doubt it. Even if it doesn’t exist.
Many audiophiles are in love with LP and tubes. They are in love with a lot of IM and THD, poor Fr. response and compressed dynamic range. Those all measure bad, but many like it.
I don’t!
I remember last concert, the guy next to me claimed to his wife, that the sound is not as good in concert sa with his LP/Tube sound system :-)

Mr. doodle

Congratulations. you have a room with better acoustics than the  Meyerson Symphony Hall in Dallas. 
Because no matter how the SACD sound engineer set the recording, with room correction, it is still playing in your room, where the sizes may be slightly smaller than the Meyerson Symphony Hall in Dallas.
Size do matter, but it is not the only parameter that matters. walls, reflections, floor etc'. Yours' at home are so much better than those at the Meyerson Symphony Hall in Dallas.
What about you invite the orchestra, to play at your home, and then you tweak the recording of that secession, with that RC and SACD and get it even better...
It would be better if you wouldn't post this pretentious post. It is ridiculously insein.  
   

"I can’t think of any reason why perfect..." artificial recorded sound, won’t sound as good or even better than the original.

Think better.

Nothing in the audio equipment industry, sounds as good as a real musical instrument playing live.

Practically, we have in Audio two main streams:
1. Claim that they are looking for a reproduction as close as possible to the real thing. (!)
2. Claim that as "1" can not be reached, they just looking for the most pleasant sound they can achieve.
None of the two claim what you claim.

They both agree that what you claim has not yet been achieved yet.

Maybe you need to listen to some live music and refresh your memory.

Digital interface of SPDIF signal is of a low Fr. nature. It may go up to 48KS/Sec, or more like 44.1KS/Sec with home equipment.
As so, cable impedance, ending connectors etc' are of less significance.
When cable do make a difference, is mostly due to a poor PLL at the receiving end. 
If the cable would be a disaster, there would be dropouts. SPDIF has no Acknowledgment of data received or massive correction methods. 
The claim it has no dropouts, but sounds less good, shows of a digital phenomena inflected over the sound...It is called jitter.
Jitter should be taken care by a circuit called PLL. All data receiving devices must have one. If the PLL is good, the cable should make no difference. If the PLL is not good enough, you are dependant on the cable. That doesn't ensure you are good. It only proves that one cable sounds better. No one claims it is now perfect!
When all digital cables sound identical, the PLL is good and it won't get better due to "digital cables".
All data transfer methods, would try to eliminate data error at transmission. So is SPDIF. The fact, that the cable gets so much attention is wrong. The inventors never meant to allow digital cable makers, make a fortune, from their poor design. The fact that we are there, and this and other threads deal with the subject, is so wrong.