Cables 101, new student, first question

I agree you have to look at the system as a whole. But you need to start your upgrade somewhere and if the interconnects can be improved, then adding one pair of better cables will certainly be an improvement.

@northman, IME, Cables are the last thing you should do to a system to improve the SQ. Some People view cables as “Jewelery” and buy for looks or bragging rights.. Spend the money on the source, a good preamp/amp and of course speakers. then address the power. after all the big money is spent, Buy cables that match the load and spec you require with good connectors. 
if your system is revealing enough, You can tell if your weak link is a cable..  Money is almost always better spent elsewhere.. Cables matter, but they don’t need to be $$$ to make a nice difference..
IME.

@soix , YES, this: "Adding a better interconnect improves the sound of my system even if there’s a lesser one elsewhere. But it also matters where you install the cables in your system." That answered my question! Thank you!

I appreciate the advice all around. I should say that I’m not upgrading my cables. I’m adding a couple things to my system so I need *new* cables. I’m trying to decide whether to move up the ladder a bit and get some nicer ones (by review and reputation) than my others, and that would only make sense if ... "adding a better interconnect could improve the sound of my system." It sounds like it does, and I will. And believe me, I'm not talking about $$$! 

@northman - I am definitely in the "cable camp"

For me, cables have provided the biggest improvements in sound in my system. Most electronics today are far better than the cables allow them to be
e.g.
- I have a $300 mini system that sound so much better after i replaced the power and speaker cables - it’s a single unit so no interconnects
- I have a Bluesound Pulse Mini streamer/speaker that sounded so much better with a good power cable, that the sales guy in the store could not believe his ears from such a simple "upgrade"

And I have repeatedly achieved this on many friends gear - to their amazement

My Bluesound NODE 2 streamer improved significantly when I added good cables. My initial interconnects cost significantly more than the streamer, but it sounded amazing - then I built my own cables

My approach is to add good cables in the following order - Speaker cables, interconnect and finally power cables

Good speaker cables allow you to hear the improvements of the interconnects and then the better Interconnects will allow you to hear the subtleties the power cables provide.

The problem is - which cables?

If you are interested in DIY I can recommend these great cables...
My Audio Alchemy (image99.net)

But if you are NOT into DIY, then take a look at KLE Innovations. Even their entry level cables are very good.

Hope that helps - Steve

I’d ask one additional question to those posting advice to the OP, here. OP asked,

In general, will the system’s sound be defined by the weakest (cable) link in the chain, in which case all the more expensive cables are a waste of money?

My question -- at what point is a "system" too un-resolving for the cables to reveal a difference?

I’ve seen many threads where people have asked about their A/V receiver and the consistent response is "get something better." So, there must be some point (in quality though not necessarily in $$) that cables are a waste of money. In other words, there is some point when "the system" in the OP’s question is not good enough. What criteria define that point? That answer, if it can be stated, would probably help people direct their resources away from cables toward more important elements in their system. Then, they can move on to cables.

That said, it looks like williewonka's post may be an example of the refutation of my premise!