It is difficult to quantify how much difference a PowerPlant makes.
The challenge is each system is different with its own issues as to incoming power.
If you readily hear the differences swapping preamps makes you will easily hear what a PowerPlant brings to a system. But, in a way, it is not dramatic. The system will sound the same with its basic personality intact, but ever so much more so.
The system sounds like it is not working any where near as hard, instrumental and vocal timbres are richer with more texture, details quietly present themselves naturally out of a blacker background, there is an effortless liquidity.
The improvement may initially disappoint as you are not hit over the head. But listen for a couple of weeks and take the PowerPlant out of the system. The sound collapses, it becomes cold and distant, uninvolving.
Keep in mind PS Audio provides for a home trial. Install the unit, listen, take it out after a couple of weeks. My expectation is you will become a convert.
(Be sure to take the transformer completely out of the system when trying the PowerPlant.)