COAX Cable Recommendations.... need some glitter

... Quick sidenote. I see various cables such as Acoustic Zed and Nordost Heimdall that are listed as COAX. It seems the coax input in my DAC and the Coax output on the Nagra Streamer are RCA....

Questions:

-Will any RCA cable work here? 

-If an adapter is required, is this something desired to avoid? no adapter? 

Thanks,

Richard

High end audio sound quality is a balance. There are a number of overall characteristics. To me one of the most important it detail / musicality. You have already noticed this. The Cardas cable calmed your overly high frequencies. High frequency dominance gives you sparkle or as you called it glitter. 

The glitter. Caution. With the ultra detailed presentation you typically get high frequency hash and overly forward (highlighted) treble and relative attenuation of the midrange.  The benefit is that you hear things you have never heard before. The down side is the music tends to become dryer, fatiguing (from the hash that you don’t hear... but just puts pressure on your ear drums), and less musical. I attended the symphony for a decade and would go in and listen as if it was my system. Wow, you want to figure out what is wrong with your system... do that. 

All of these system issues are intolerable to me now. I learned slowly about them by relentless pursuit of detail and imaging, without understanding of the down side. So, I’m just recommending to be aware of the down side. I’d recommend listing to some real acoustic instrumental music and noting how forward the treble actually is... how so much is powerful midrange, if you reproduce this ... you’ll get the music... what you want to move your foot, sway, and get lost in. 

Coax = RCA... RCA refers to the plug ends and coax is the wire configuration... as opposed to XLR with three conductors. 

Hello @whyrichard , as usual, @ghdprentice is giving sage advice.  You did say 'calm the shrill' so maybe we are agreeing, but glitter often does coincide with harsh, fatiguing overextended highs which at first sound amazing and then lead to listening fatigue.  Its ok, I call the goodness in my system 'sparkle' and to me it means resolving but without glare or fatigue.

Looking at the newer Nagra streamer, it has USB and coax outputs.  You need to pick which one is best for your DAC.  But build materials of the cable do matter.  For me, all copper cables are smoother than any I have tried with silver in them.

I have used excellent digital cables from Network Acoustics, and my favorite, a Realization  from Kubala Sosna.

And yes, Digital Coax cables use an RCA connector, but the cable should be built specifically for digital.

For a coaxial digital cable, you want a precision-engineered 75-ohm cable with uniform impedance (incl. connector) to ensure accurate signal transmission and to prevent signal reflections caused by impedance mismatches with input/output devices. This requirement is less critical for analog applications.

Second, look for insulation with a low dielectric constant. The dielectric constant of vacuum and air is close to 1.0, while Teflon (PTFE) is around 2.0. Air-injected Teflon insulation can reduce the effective dielectric constant to around 1.4–1.5. Some products have developed such lower dielectric materials, which can significantly improve signal transmission, especially at high frequencies. Look for cables using such materials.

Once the impedance rating is matched, ideal length that people refer as 1.5-2.0 m can be less restrictive because the reflection is minimized.  If cable is high quality, well-shielded and imp. matched, 1 m is just fine and will perform equally well.

The USB looks like it’s only an input on the Nagra, and the only outputs are SPDIF (RCA) and their proprietary N-Link.  You’ve gotten some sage advice about not going too far in making things sound brighter as it can be like putting too much salt on your food.  I’d suggest buying this used Acoustic Zen MC2 at $200 that is a very good price, but do this now if you’re so inclined because it won’t last long and frankly I’m amazed it’s still available.  Read all the glowing reviews — I have this cable and agree with their assessments.  This is an extremely balanced and capable all-around cable, and you could use it as a benchmark against other cables and if you find something better you can very likely sell it for at least $50 more than you bought it for.  Nordost would be one to try for a more detailed presentation, but others I would look into are Snake River Audio, Jena Labs, Mad Scientist, and of course there’s also the Cardas Clear.  In any event, having the MC2 on hand would be super helpful because you know if you find something better it’s truly special.  Just my $0.02 FWIW, and best of luck. 

This coax shootout is a bit old, but may be helpful