I know there's a lot of debate about how much of a difference high-quality cables etc make and while I'm skeptical, I've decided to take a listen for myself.
My question is, if I were just going to upgrade one thing, what should it be? I'm pretty comfortable with the big pieces in my chain -- Macbook, Cowon iAudio7, or Sansa Clip; feeding some combo Asgard, NuForce HDP, cable DAC. But I have stock cables on all my headphones (HD650, HE-400, Shure SE 315) and basic Radio Shack'ish cheapies for interconnects.
What will make the biggest difference: headphone cable, interconnect, power cord? Again, I'm skeptical about all this but curious so if I were to invest, say, $50-$75 or so, what's my best chance of hearing a difference?