Wow, no nay-sayers yet. Fritz, after playing with designing power cords, it seems that good power cords need to have decent guage, good purity of conductor, good dialectric, shielding and a geometry that provides common mode rejection. The effect seems to be similar to a power conditioner, yet without the limiting of dynamics that you get with most conditioners. If indeed there is a conditioning effect then this might explain why there is a beneficial effect when changing the last meter. Either way, the effect is noticeable and as reported above, not always beneficial.