There is no compelling evidence that two different cables will detract from the sound of your speakers. In fact, as many have testified, you can exploit the strengths of very different cables to achieve the best combination. It just makes sense that, as different as speaker cables can be, you would use the best, probably heaviest, cable for low end and best, probably smaller gauge, cable for highs. I even use a shotgun combination incorporating two different cables for the lows, albeit both are from same manufacturer, AQ. This seems to provide a lot of deep bass, with very good transient response. Double run of Slate gave very fast bass with no overhang, but not terribly deep. Double run of Midnight gave lower bass, but leading edge of transients was muffled and some lingering boom. Combined the two in true shotgun configuration, and voila! Deep bass with sharp attack.