I went through this with my krell ksa80 and thiel 3.6's. the problem is that in search for linear accuracy, the thiels are lasers that burn a hole in the middle of your forehead. To sound right, a speaker should roll off slightly in an anechoic chamber. You are trying to use a cable as a tone control to offset this. I eventually ditched the system and started over with tubes
sorry.
sorry.