I have the Ebtech Swizz Army tester as well--absolutely essential gear for the studio. The test tones are a tremendous troubleshooting tool, and of course I test every cable before I connect it to my gear.
Unlike what other posters think, I believe you are doing the right thing by upgrading your cabling. In my experience, the difference cable makes is a cumulative thing. If you listen to one cable against one other cable, it's not necessarily easy to hear the difference (although in some cases it is). But when you have hundreds of cables, using the good stuff can improve the overall sound and at the very least, reliability.
Avoid any cable with the plastic molded ends. Even in studio situations, where they won't get moved around much, they have a high rate of failure. When I still had that stuff around, whenever there was a mystery missing sound it always seemed to be some equipment on the other end of one of those molded plastic cables. I now use Mogami, Canare, Horizon lo-z, and Connectronics cables throughout my studio. All with proper metal ends. Sounds good and literally no problems with cables dying so far.