I've accumulated several sets of strings over the last couple of years I started with the double bass. For me, I enjoy playing the heavy strings. But I do change them around...going from my original flatchromes to my light Helicores and medium Flexocores in a random pattern. I notice a change in what I hear from my bass, though, when I do this: lighter strings give this scooped midrange sound (like the old Metallica records), where the heavier strings increase the midrange. Is this what heavier strings should accomplish on their own, to push the midrange up? Maybe this is all moot, since I'm only hearing the bass from where my own ears are.