I had the RGPC 600 along with 400s and the power cords etc. After a lot of listening, tweeking and what have you; I concluded that I was experiencing the same negative elements that were spelled out in Stereophile's review by Fremer. Transformers parading as power conditioners can be real trouble in many systems. With so many good choices, why go with something that has a patchy track record up to this point??