'' Okay let me ask my digital question in another way ''........

Just a suggestion, but it might help if you included the phrase “Esoteric Owners” in your title, since you are asking a highly specialized question for a small target audience within the community.
  Does Esoteric have a support group on Social Media?  I have found the Qobuz Facebook support group more helpful than asking the company any question.  Melco’s Facebook community is also superb, with people all over the globe answering anything I post with helpful information usually within minutes.
  Fwiw, I read reviews from 2 U.K. reviewers that I respect about dcs
and the master clock that they sell for their stack.  Keep in mind that this separate clock costs around 10K, and these 2 reviewers both preferred the dCS without the clock.  At a more prosaic price point, I once owned a Wyred4 Sound DAC that then offered a separate master clock, which I purchased and then returned.  It didn’t worsen the sound, but it didn’t seem to do anything that I could perceive with my ears, except lighten my wallet.

Good morning Mr. Mahler 123  -  thank you for your response and also thank you for the suggestion. I have been doing a ton of research on this topic and the reason that some of these master clocks when added on  '' don't work sonically '' is due to the question that I have presented. There are difference in the signal being made ; sine vs square. The MUTEC Ref 10 SE 120 Master Clock is an incredible product and unbelievably engineered and I am looking at that over staying in the Esoteric line. But ...but... its signal is a square wave and even though Esoteric players will accept both signals  …...it does effect the overall sound. Sometimes good and sometimes bad. I am looking for someone here who has gone through what I am looking at now and has an educated and accurate response.                

I recently purchased audiophile network switch with TXCO clock, rest of streaming and network optimized prior to the switch purchase. Extremely disappointed with switch in system, yes, there was lower noise floor. The one great defect of the switch and added clock was image outline excessively sharpened, like cookie cutter images. I've surmised this was clock issue, as I've heard previous clock upgrades affect sound stage and imaging. Perhaps DCS owners and mahler123 heard this same defect.

I don't recall having previously heard about square vs sine wave signal mismatch, could be my issue. I'd assume the dcs folks had no such mismatch.

Thanks sns much appreciated. This is why I am doing my home work before buying anything. The MUTEC clock is a XCXO oscillator which if we a are talking about the same thing is different. There is a lot in adding a clock as they must match. I hope things work out for you and thank you.  

Just out of curiosity where did you find out the Esoteric clock input can take a square wave the manual says 0.5 to 1.0 Vrms sine wave. 

Mutec you're looking at has OXCO clock, oven controlled oscillator, this is superior to TXCO in my switch, My dac runs OXCO clock for usb input. Widely varied opinions on clocks leads me to suspect there can be possible overuse of clocks in individual systems. Result is an excess of image, sound stage precision, in my case, loss of spaciousness, airiness. In real life, individual performers or images blend into one another. Image quality of my system sans switch/clock replicates this, With switch/clock in system, its like individual performers in segregated anechoic sound booths .
YMMV

Broadly speaking, a square wave output tends to be more stable. It's inflection points are more clearly defined.  With a sine wave the clock often cannot always  pick the exact same inflection points.  However, as usual 'it depends'. So you need more research.

I have just bot a great square wave cybershaft based clock that outputs to all 4 items in my digital system. The result is staggering, so don't give upon this search.  It was from afterdark and outputs both word clock to my dCS NB and 10M to the other components. Prices way more real world than mutec.

I would suggest you post your query on on the audiophilestyle forum....there are many, many pages that refer and qualified users who are extremely helpful.  Another useful resource is the Hong Kong afterdark site.  Confusing but lots of info.

By the way, I had just about decided to stop posting here as there are so many flatearthers on this site who are very rude about subjects they have no clue about...and then along comes your question!

Best wishes with your search.

Garebear,  go to the "What's Best In Audio" site, where there is an Esoteric owners forum and also a digital forum with clock discussions among guys who spend a lot of money on their systems.  You will find your answers there. 

So my question is - '' has anybody out there added a MUTEC Ref 10 or Ref 10 SE 120 to an Esoteric K-01XD CD player and what where the sonic results '' ?  Thank you ……. 

Likely no one out there to directly answer your question. In the end, likely you're going to have to purchase Mutec to find out.

If you end up trying a clock, I for one would appreciate giving us your results as it adds to knowledge base. Based on my negative results, I'm interested in hearing other perceptions of how clocks affect sound quality.
It is good none of the 'all knowing' haven't yet entered discussion.

......good morning SNA and I have contacted Mutec and presented my question to them as I did with Esoteric and will see how they respond. Yes it is nice not having the usual '' scribes '' chime in as this dilemma is more direct and factual as opposed to their usual arena which is subjective and of their own opinions  - and that's just want the are ; their opinions. Thank you again and stay safe and I will follow up …..