I use Synergistic Research cables with my Levinson with excellent results. There is a way to change the powercord on your 336. You will have to cut the powercord off at about 8 inches. Then attach a male IEC connection. Nw you can plug a power cord in! This works very well, I owned a 336 at one time and modified it in this way. You could also remove the cover, find the taps where the current power cable is attached, cut off the end of the power cable you want to use and wire it direct. However I believe the first method would be the best.
Hope this helps!
Sgr