I've bought a Silver Poison cable for my HE-500 plus an adapter.
And the improvement is amazing. I was happy with my CLAS + ALO RX MK3 + HE-500 to start with but boy was I wrong... There is nothing subtle about the change in sound. Everything feels better, clearer, more defined, details that was never there before, now... are. The cable isn't as stiff and not that much heavier either so its more comfortable to use and easier to handle than the stock cable. Plus Franks cable is built much better and will last longer. So now I have to listen through all my albums again.
I think Frank and his product is fantastic. And that is why I have a big package arriving in a few weeks, from Frank, with some things that will most likely make me want to listen to my music again for even more details. That 35 pound package cannot get here soon enough...