I've used Kiwame brand resistors in several builds now, too. I don't know how much of the sound I can attribute directly to the resistors, but those amps didn't sound like crap.
Really, how many people out there can truly distinguish between two different resistors? You'd have to build the same circuit with the same layout, with perfectly matched sets of tubes (or transistors, I guess) and then swap those two builds within the same system to A/B them. That's more messing around than I'm willing to go through. That's why I'm not claiming to know much here.