So, now there's a qualifier in "adequate size", huh? Next thing it'll be copper, single-stranded, shielded cables with spade connectors of "adequate size". Sarcasm aside, Steve has actually begun to answer his own question.
There's more to some cables than just a length of wire and some connectors. The design and materials used, including gauge, quality and combination, all matter. Known issues like skin effect also have to be considered. Differences in equipment insert variances like impedence which also make a difference. Let's throw in quality of workmanship just to confuse things a little more, too. I'm also not convinced that "science" has it all figured out, either; new things are being discovered much to often to fall into that trap. All of these know and unknown variables contribute to the end product and how it performs, and not just with cables. Some exhibit minor differences, some more pronounced changes. Ultimately, it's a summ of the whole, not just one specific thing.
Depending on one's combination of system and desires zip cord *may* actually be adequate. So, while it would seem silly to spend $2,000 on cables for a $1,000 system, it's even more silly to buy a $20,000 system and only spend $50 on cables IF THERE IS SOMETHING THAT SOUNDS BETTER.
To use an auto analogy, a Yugo will get you from Point A to Point B. A Mercedes Benz does the same thing, just differently. The question one has to ask themself is at what point does a better car become overkill? Same thing applies to cables.
Finding what works best requires experimentation. Because personal taste and system synergy are such key elements in this matching the truth is in the hearing. This is one case where meters lie because they can't measure what my brain hears. so, if zip cord works, use it. I personally found it to be too limiting in my system (a fact that was verified by to other's) and opted for something better.
