I’m a bit confused about your question. Generally, systems put together for high fidelity will be interconnected with speaker cables... built to sound good as opposed just some off the shelf wire with a material requirement.
Since it sounds like you have a home theater... guessing now... from which you also listen to music. Then you should invest in speaker cables made for the purpose. I recommend looking into Cardas and DHLabs speaker cables.
For me, I have pretty good quality speaker cables attached to the front three channels and then, the same brand, but lower quality bulk cable for the other channels.
Given the sonic characteristics of the Marantz and Focal, I recommend looking at Cardas. But ether of these are likely to improve the sonic characteristics of your system for music. It may also be very obvious for HT. But HT is generally less important because one is distracted by the video. But if you are comparing to really cheap wire... then you will probably find it a noticeable improvement.