My limited experience placing anything between the amp and CDP resulted in diminished dynamics and/or a softening, albeit slightly, of the sound.
The best one was a simple Blue Circle Thingee FX2 but it still had a slightly negative effect. Out of the blue, I used it as a stand alone device plugged into an open outlet on a Cullen Cable power strip (no filtering or conditioning) and the results were wonderful.
I never thought there'd be that much noise on my lines but there it was, plain enough for anyone to hear. Better decay, detail, air, extension, tighter base, and so on. It's easy to determine by unplugging and plugging it back in as the resultant change in sound is immediate.
The power strip has a built in 4' power cord and the Blue Circle Thingee"s IEC uses a 6' power cable for a total of 10' to the outlet. Bypassing the power strip and going straight into the open outlet on the wall subtracted 4' of power cord.
The odd thing is, there was more attack and leading edge with a lessening of body in the mids and base. It seems there's too much filtering happening, or something more than filtering happening, when placed closer to an outlet that parallels what happens when the unit is used as an inline device.
That tells me that having dedicated lines is more important than filtering or conditioning close to the sound source. I've read where some manufacturers don't stop at filtering/conditioning but try to give audiophiles a certain type of sound that's appealing when they should just be content with cleaning up AC noise. It's quite the jungle out there when it comes to this.
All the best,