Power cord into power amp

I have had the same experience. It appears that power conditioning is a system to system thing. In general those of us with dedicated lines find it makes things worse. I can remember thinking my Tice Power Block helped on other components beside power amp when I was not using a dedicated line. There are several possible reasons I can think of and probably a lot more. One is that the conditioner does not have sufficient capacity for the amp. Amps can draw really amazing amounts of current for short periods of time. I just replaced the power cord on my Musical Fidelity NuVista amp , which was large, with a much larger one and got an immediate and very noticeable improvement. But others have reported little or no improvement by changing power cords. In HIFICritic recently a stock cheapie cord outperformed some expensive ones on a CD player. On Power amps the high priced ones were better. A whole group of reasons can be lumped together under the heading " Don't put anything in the line that you can leave out" You may be improving on area at the expense of another. There is so much out there on this that all I can say is that there is simply no consensus on almost any aspect of it. There are several interesting approaches, The "Never Connected" method interests me. But unless you have a large amount of time to spend doing research on it the best thing is to use what sounds better and forget about it.