Do I need an expensive digital cable?

@audio-b-dog 

When you asked what I did in my system, I replied that I now exclusively use native HDMI for all digital interconnections between components.  Absolutely not I2S over HDMI, and not any variety of S/PDIF.

S/PDIF is only designed for two channel PCM. Lack of any data error detection or correction implies that a really bad cable could definitely affect the digital transmission between your CD acting as a transport and your DAC. I have no way of guessing what the threshold of really bad is, in your system.

Equally I have no way of guessing the effects of EMI on your coaxial cable, or from your cable to other components.  Note that balanced twisted pairs in theory eliminate the effects of EMI, and need no shielding.  Shielding increases the capacitance of a cable, altering its analogue frequency response.

All I can say with some certainty is that your "bits are bits and are double corrected" is a false assertion in the S/PDIF context.  What matters is that you are hearing differences that are real to you. Physics supplies supporting reasons for differences you hear, but not necessarily your characterisation as "smeared".

Note that HDMI uses unshielded twisted pairs for very high speed digital transmission.  So do later incarnations of Ethernet from 10BASE-T on. This is why one of the HDMI pairs can be used for Ethernet.

Think about what happens when you make cables longer. Eventually they don’t work. Sometime before not working at all they will not sound good!

@richardbrand 

Thank you for the information. Unfortunately, I can't use HDMI on my sytem. I'm kind of at my limit dollar-wise. I read reviews of my cable and they were pretty good. I was listening to a CD and it sounded really good. Very present. At 44.1 it sounds close to a record. So, I guess my "expensive" ($249) cable is okay. But I think from my test and from your expertise on networking, I can conclude that a person should purchase something more expensive than the bottom-of-the-line $14 coax cable. 

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@audio-b-dog 

From my perspective, North Americans in particular have been fed several loads of garbage, including

1. There’s no aural advantage in going to more than 2-channels
2. SACD has failed in the market
3. SACD players only need to output 2-channels
4. SACD transports are expensive
5. HDMI blocks SACD content
6. Expensive HDMI cables are better than inexpensive ones
7. I2S is all you need for digital transfers

Happy to expand on each of these points if anybody is interested.

@richardbrand 

My McCormack UDP-1 is a multi-disk player, CD, SACD, DVDA. From my experience a well-recorded CD sounds better than SACD. My Moon 280D streamer will not receive anything but a CD signal from the McCormack. I have set up another channel on my preamp for SACD and DVDA. I do not play them for a better sound. I play them when I want to hear whatever is recorded on them. The Lynne Arriale CD I told you about sounds better than any SACD. I do have one Fleetwood Mac DVDA that sounds fantastic. But maybe it would sound just as good on CD? So, my empirical knowledge agrees with your theoretical knowledge. Maybe we can work on my physics theories. I believe that space is the prime element in the universe, and that everything comes from space. 

@audio-b-dog 

Maybe we can work on my physics theories. I believe that space is the prime element in the universe, and that everything comes from space

You are absolutely right on this one!

In a rather strange way, space is negative energy.  I'll try and explain this below.

Given that physics believes that in our universe, energy is conserved. When more space is created (more negative energy), a balancing amount of positive energy must be created.  After the big bang, which created space, some of this balancing positive energy condensed into the matter we are familiar with - protons, neutrons, electrons.  Some of it exists as electromagnetic waves.  Some of it we cannot account for at the moment.

Quantum theory contends that there is no such thing as truly empty space - subatomic particles appear and are annihilated out of otherwise 'empty space'.

How can space be negative energy?  Imagine you are standing in a level field.  Somebody digs a big hole alongside you (creating space).  You have now acquired potential energy which you can use by falling into the hole, which represents negative energy.

The starting conditions for the big bang involve about an ounce of matter, incredibly hot and small.  From this, all the space-time we can observe, and all the stars and galaxies in it, arise naturally from the balance of energy between things and space.