I'm confused about your objectives. Are you trying to ascertain that the cables do or do not sound different, or prove that your test subjects can't tell cables apart? Those are actually very different objectives. You should always clearly and simply define the objective, preferably a single one. You won't get good resolution on the comparisons because the transition takes far too long. As has already been mentioned, auditory memory is very, very short. For best comparison results the transition time should be no more than a few milliseconds. As you can see, that would required construction of some rather specialized equipment. With you handling the switching and the cable choice with full knowledge of what they are, there is a serious lack of control, and it certainly won't be a true blind test. You will be introducing a massive amount of bias...your own...consciously or not. A true ABX/DBT eliminates the knowledge of the X choice from everyone involved until the data is collected and compiled. You no doubt fully anticipate the test subjects will "fail" the test, and that in itself is a bias. A true ABX/DBT has no pass/fail, it just generates subjective data. Every trial produces a good data point, so there is no "fail" as such. The test may be fun, but will technically be inconclusive because of the lack of controls, presence of biases, and massively long switch time. My guess is you'll receive objections and challenges to your test.