It is often recommended that amps not be plugged into power conditioners because it can limit the amount of electricity available to them, which sounds like what is happening to you. There are power conditioners made to have amps plugged into them.
I’d listen to your DAC and CD player with and without power conditioning (they draw less power than your amp) and decide if it’s helping or not. As with everything else audio, you have to try something in your own system to see if it works in your situation.