Just got the Ross Martin DAC

I see nothing wrong clocking from SPDIF, never made bad experiences from this. SPDIF/AES clocking is pretty stable from the ADs i have tested until now.
You can only have one clocking master. May it be the wordclock in or the digital audio signal embedded clock signal over SPDIF/AES or ADAT. I would use WC preferably only if there is need to sync more devices in more complex configurations, or with some older equipment, like a house clock, and even then i would try to make my main ADC the master, not an external dedicated clock. No matter, what others or the hype says. *Maybe* using a distribution amplifier box for this ADC clock, but no external clock.

Best regards,
Martin

Ah isn't the thread about DA ?

describing the AD loop kind of confuses everything

So for DA a long recognized small area of concern with apollo, the signal in apollo is digital so its sent to RM on spdif and the RM is master clock as its converters are final conversion ?

Sorry but i am having trouble visualizing the signal path: interface to RM and then to monitors ?

Thx !

Does that DAC have the National LME opamps or did you pop for the Analog Devices ADA 4898-1 opamps? Mine was the first done with the AD chips per my request. They are offered as an upgrade I would recommend.

Also, the S/PDIF cable will have a large effect on the results. Canare and Mogami make 75 ohm S/PDIF cable. Terminate those with Canare F-10 RCA connectors, those are also made at 75 ohm impedance. Avoid 'hi-fi' RCA cables, too slow, too much stray capacitance and the wrong impedance.

The best S/PDIF cable I've used is the Kimber pure silver coax. Yes, it is expensive, but nothing else is as revealing.

Sounds correct, I think.

This is an interesting question indeed, Johnkenn, and i have to admit that i have no reliable answer to that.
Maybe the only one who can give it is Ross Martin himself.
If I would build this kind of DAC, and i build in a good clock, i would use asynchronous clocking except if there's a signal on the wordclock in (auto-sensed) or use switches to let the user decide.
NOT that i ever built a DAC, or planned to do so, or feel capable to do it in a professional way at all ... i am not too deep into this matter and most of what i make in terms of clocking setup is from trial&error really and a bit of technical reading in the past...
So i can only make vague educated guesses on how your (or my) RM DAC handles different clock sources internally - not more.
All depends on the clocking circuitry used outside the ADC chip and what is fed into it as system clock...and i do not know how the RM converters handle this in detail.
So, Ross Martin is the man to ask, really....
Sorry i couldn't be more helpful here.

Best regards,
Martin

Yeah when I first ordered mine I think I was on his site for like 30 minutes ! At first its really confusing but then you crack the RM code and figure out whats going on over there . 

Standard hi fi RCA connectors are about 24 ohms. It is beneficial to use the proper temination impedance. Canare F-10 connectors are not very expensive and are worth using.

Toslink is also ok, if you use quality fiber optic connectors. I use pure glass fiber optic cables here and they sound better than the plastic versions.

Yes, some will balk at the cost of a Kimber pure silver coax S/PDIF cable. None balk at the sonics though.
If you are a home guy, pay your bills first. If you are a pro, it's another tool in the box. When someone spends $$$ on a certain mic pre, box or processor, it's usually determined to be valuable. A cable that improves the sound of your entire production for under $300 seems to be a very good value to me since it will not wear out and will last for many projects.
YMMV.