@millercarbon is quite right. An expensive interconnect can have a component level effect on a system. I have had three systems around for a long time. Occasionally I’ll swap some rediculously expensive cable into one of my less expensive systems, it might have big improvement, none, or sound simply atrocious. But typically a component needs to be of a very high sound quality before real positive results are gained.
As you obviously realized you can put a lot of effort put into assembling a good system. If you are willing to work like a mad man, you can assemble a great system for less money... but it takes tremendous effort. MC has put in the effort. But it takes effort and time... years learning how to listen, understanding sound, components, interactions. It is pretty easy in the beginning to make mistakes and get yourself into a negative feedback loop.
Hence, some basic rules of thumb can help. Hence, the idea of 10 - 15% investment in interconnects. The idea is you need a bit of guidance at the beginning. Plunking down $5K for interconnects for a $5K component is not something guaranteed to be a good investment. On the other hand some of the really inexpensive cables recommended here are also no better than what is supplied by the manufacturer. Until you really know what you are doing it is probably going to be true that putting an extra $5K into a well chosen component (valued at $5K) is a better investment than using that $5K in a set of interconnects. Typically a well chosen $10K component will sound far superior (big difference) to a equivalent $5K component.
The best strategy is to invest in the very best possible, compatible components. Get to know them intimately, inside and out... while saving money (for the next phase of the process). Then look for and evaluate interconnects and cables... this is a very time consuming ( and fun... hopefully) process. Then tweak... isolation, power cords, etc. if you try to do too icy at once it becomes really confusing... especially if new to this. I have spent literally thousands of hours evaluation components, interconnects and tweaks over the last 50 years... so has MC.
I have also swapped an expensive cable into a system and literally have a jaw dropping, component level change in the sound... but that is not the most common change.
