How good does my system have to be to realize an improvement with cables?

I have a 2.5k cable on a realistic receiver from the 70s. The difference in sound quality is mind blowing. Smokes my buddies 40k gryphon system. 

@stevewharton - I used all Blue Jeans Cables for a long time because they are very well made, affordable, and they are fairly local for me so overnight delivery is almost the standard.

I was surprised at the difference (improvement to my ears) that I heard between the BJC LC-1 ($50) and the Audioquest Chicago ($100) and then Sydney ($200).

Or put a different way How would you know if your cables are your weakest link?

Start with the cheapest Best Buy cables and if the expensive ones make no difference, then job done.

It is pretty easy to spend more than 10% even doing DIY cables, on gear that is not super expensive. I must have spent over $1000 on cables an ICs between the wire and the ends in the last couple of years… and that was for DIY cables. Easy to do ~$40-50 on a DIY IC, and more if one is using silver wire instead of Mogami or Cardas etc. wire.

Usually I have found that moving the speakers a few inches makes more of a difference than I have noticed with cables.

I’d likely buy BlueJeans if I did not have a soldering iron.

Wouldn't that $200 be better spent on a better component? 

Bingo!
We have a winner.

Thanks everyone for the input.  My biggest issue is I don't know what I don't know.  I'm budget cable all the way and it still sounds good to me, so considering buying a cables that cost more than half  of what I spent on my amp causes me pause.

I like the concept of the used the route but counterfeit looms as they are selling for more than the ones from China with the same look.

There are sooo many choices and feedback from all of you and the logic of how you made your decision is of great value to me. 

Cheers

OP,

Yep, you got it. Hopefully you take the complexity as a challenge and enjoy getting the most out of your system through listening and learning. That is what drives most of us.

I am sure over my lifetime I have spent over a thousand hours, testing, evaluating and reading about different cables. They have made major contributions to the overall sound quality of all my systems. To calm down the harshness and high frequency tipped sound when my components were inexpensive and now to be incredibly transparent to bring through the full capability of my outstanding components.