Cable advice

The manufacturers have incentive to suggest that all cables be the same.  Since each set has a different purpose and often different impedances in play, you could be very likely get best sound with different cables.

You will receive varying opinions regarding your question. I really don't think there is any one correct answer it all depends on each person's equipment and the synergy developed between components and cabling. I have systems that I like that are all from the same manufacturer and other systems that I achieved the sound I personally wanted by carefully mixing and matching various manufacturers' cables. In case you have not guessed I say nay to those that insist that cables should not be used for tuning, but you have the right to your own opinion ;-)

In my experience it takes time and listening tests, trying different cables until you achieve the level of synergy that suits your preferences. This may or may not be a full loom. 

I also have four different brands currently. IMO it's a good idea to start with one inexpensive brand throughout as a baseline then choose one component to try different cables on,usually the source first.

Think about this. The internal wiring inside each of your components is different.

While keeping the same cable brand and type may be one approach, with some of the higher quality cable brands/types, intermixing can also produce good results.