Freebie Cable Synergy

In the midst of saving my pennies for a new digital front end, I decided, what the hell, to try swapping out my Tributaries silver interconnect for one of the cheap freebie cables I've had sitting around and never used. The result? The harsh, treble glare that's been bugging me disappeared, and in its place I found a smooth, clear, and well extended top end--cymbals on CD sound like cymbals for the first time in my system. I also found a broader, deeper soundstage and a much greater sense of microdynamics on quiet passages. The only thing that didn't improve was the low end, which was about the same. Popped the Tributaries back in, and everything compressed and got harsh again. Tried the Tributaries on my vinyl rig, which has always had a cheapie cable due to budgetary constraints, and it had the same effect.

My gear's not pricey--Marantz CC3000 changer, NAD C325BEE, KEF Q15s, and 12g copper Tributaries speaker wire--but what I'm hearing suggests to me something more at play than just the cheaper cable rounding off the budget CDP's high end (or doing the same to my vinyl) while the silver accentuates it. I believe cables can make a difference, and I'm likely to go cable hunting when I buy a new CDP, but I'm wondering if anyone has had a similar experience with freebies or the Tributaries, can explain it, or can offer other cabling suggestions for a guy on a budget trying to get the most out of his rig.