I built a power cord using Belden 19064 (I think) cable, a right angle plug to go to the amp, Wattgate for the power strip, covered with techflex. The cable is shielded and I find the noise floor reduced. The point is the Crack does respond to power cord differences
Crack/Speedball, SEX 2.1/C4S, Bryston BHA-1
Sennheiser HD600/Cardas cable, Beyerdynamic T1 2nd Gen, Hifimam HE560/Hifiman balanced cable