Does using same brand cables improve performance?

When you mix componets from several manufacturers it's not unusual to have to deal with 'hums and buzzes' and minor problems of all different sorts. Mixing cables can likewise be a challenge with the benefits of one cable cancelling out the benefits of another. Manufacturers have certain design characteristics that result in a synergy when used together. I have validated this several times over using clusters of componets from Audio Research, Jeff Rowland and in lesser systems from Rotel and NAD. Mixing these brands never produced as satisfying a result as keeping the brand consistent where possible.

As a cable manufacturer, it may come as a surprise that I agree with the Balderdash comment. Each interface is its own problem and therefore may need a unique solution. I wouldn't go so far as to say that you can put a syrupy, rolled off cable together with a bright cable and get anything coherent. But each step in your audio chain is likely to present a different challenge in terms of mating output impedence with input impedence, as well as potential phase related issues. It is also not true to assume because a manufacturer's interconnects are great that therefore their speaker cables will be great too. To be ompetitive in the cable field these days you really need to come up with something of a breakthrough, not just apply conventional wisdom. The breakthrough that makes your interconnects special is unlikely to have the same, or perhaps any, relevance to speaker cables. For each interface in your system you need to find the cable that enables the music to be a combination of lively, well-balanced, with nice black backgrounds (these are the things that will be right when you have the interface right). The rest of the characteristics of the cable are the house sound and you either like it or you don't. Lack of liveliness, phase related anomolies (which we perceive as tonal abberations) or grain are an indication that the cable is not a good electrical match for the particular interface. All of tyhis is just my opinion, of course, and I love it that we all perceive the world differently.

I have discovered that there is definitely a synergy, at least in my system, with SR active-shielded cables. I would also mostly agree with the Balderdash comment, since I too have a pile of cables from different manufacturers that seemed the best for various components at different times. Various manufacturers may have a particular "house" sound that you like, which is another thing to keep in mind.

There is excellent advice being given by the prior posters. Regardless of what brand or brands you decide on, demoing in your system is the best way to find out what you like and what fits the best with your particular musical tastes. Good luck.