Recommendation for Digital Coax

Why not optical?

plenty of reasons, the search bar above is your friend

Well, I decided to try the cable recommended by soix. Always go with 1.5 M.

Transparent Cable is a good option 

Big +1 @ghdprentice that optical adds two additional and unnecessary conversions .

@mesch good choice and think you’ll be pleased. Make sure you pay attention to the directional arrows, which on my cable are faint and hard to see. I inadvertently installed it backwards once and my system literally sounded broken until I figured out my mistake. Ugh.  Please report back with your impressions if you would.

Optical is the most accurate, efficient way to transfer data from point a to point b, undisturbed.

If you are looking at optical to be used for data transfer, such as computer, then yes, optical is the cleanest way to get data from one point to another.  However, even optical has distance limits.

That being said, optical is not perfect.  The problem is that the LED emitters just cannot light up fast enough to create a perfect square wave pulse.  Lampizator did tests on this and compared it to several COAX transports.  The waveform from optical ended up being this very distorted curvy waveform (almost like a sine wave).  He was amazed that the receiver could translate this into pulses at all.

Under listening tests, optical can sound pretty okay with a good glass fiber cable.  However, even a cheap copper based coax like the Blue Jean Beldon will have more life and engagement in the music.  Everyone can have their own opinions and some may prefer optical in their own system.