I have seen a lot of pervading posts suggesting that "it doesn't matter what quality of digital cable you buy because digital cables either work or they don't work."
This simply is not true.
While I do agree with the overall sentiment of this statement in regards to over-priced cables, this statement is not correct; and I would like to offer some words to steer the general public away from this myth.
Digital signals transmitted through the air or even through a cable can, in fact, be corrupted by electromagnetic radiation and otherwise induced voltages. If this wasn't the case, then we wouldn't need things like "error correcting" bits and protocols to handle digital signal errors.
While it is true that the integrity of a digital signal is far superior to an analog signal, a digital transmission can still produce less than optimal results but still be considered as "working". If you don't believe this, consider your cell phone and the types of resulting quality you get at any given time; A cell phone uses all digital transmission and processing.
A digital signal transmitted through a cable does suffer LESS from typical forms of electromagnetic interference but it is not totally immune. An inferior HDMI cable, for example, could cause pixel drop outs, reduced color fidelity, picture artifacts, and audio artifacts if the circuitry on either end of the cable is not robust enough to handle the errors.
As an aside, most people don't understand the difference between a $1000 DVD player and a $50 DVD player. In part, it is the quality and robustness of the internal circuitry to effectively process the digital signals. If digital signals either worked or they didn't work, then you wouldn't see a quality difference between various DVD players or other components.
I think where people are coming from is this: Exactly how much should you be expected to pay for an acceptable quality digital cable? And is a $20 HDMI cable as good as a $100 HDMI cable?
The big factors that determine a cable's quality are the materials used for shielding, the type of shielding, the quality of the internal conductors, the internal arrangement of the conductors, the length of the cable, and the quality of the interfacing connectors on the ends. Most people seem to understand that shorter cables will have less issues than cables with longer lengths.
Historically, there have been two major camps of consumers: There are those that would like to enjoy the new level of quality but without the fuss of nit-picking over all the inner workings (my mom and dad, for example). I understand and appreciate this. Alternatively, there are those that want to push the technology to its fullest capacity to squeeze EVERY OUNCE of quality possible from the technology (all of us know someone like this). The engineering part of me appreciates this too.
There IS a potential difference between the quality of circuitry and signal processing in DVD players (and all audio/video components). Likewise, transmitting and moving digital signals around can be accomplished in varying degrees of quality and attention to detail as well.
For those attempting to milk the technology for everything it's got, the entire chain of components from player, to receiver, to cables, to display, to speakers has to be of the utmost quality. Any weak link in the chain diminishes the potential quality of the other devices. For these types of users, pristine quality cables are a must because their equipment is generally more sensitive.
But for most, that same pristine quality cable is going to be overkill given the types of equipment they are connecting. For example, using 4 AWG Monster speaker cable to connect a cheap audio device to its 20 Watt speakers is not going to result in any quality improvement whatsoever. In a similar fashion, I agree that there are going to be a class of digital cables that simply "work or don't work" because the weak link in the chain of equipment is not going to be the cable itself.
Now, from a practical standpoint, I would offer this:
* If your cable comes packaged in anything other than a simple plastic bag, simple box, or envelope, you've paid far too much. (Wise words, not my own.) i.e. Best Buy, Circuit City, Crutchfield, etc.
* Monster Cables ARE good cables, but they ARE ALSO too expensive, and maybe overkill in a lot "typical" environments in which they are used by consumers.
* Try RAM Electronics (http://www.ramelectronics.net) or MonoPrice (http://www.monoprice.com) for quality cables at good prices. Other good cables are by Gefen, Comects, and Wireworld. I prefer RAM for price/quality.
* Here are HDMI cables reviewed by those who hate paying too much for cables (mostly geared toward long lengths): http://www.hometheaterhifi.com/other/cable-benchmark/hdmi-cable-benchmark.html
Thanks for reading!
"Now let's cuddle up and watch that movie... because sometimes spooning leads to forking."
B.S. EE, M.S. EE/CS
Los Angeles, CA