Laynes- I fail to understand what in your post is the actual SQ problem?
Your PL has noise suppression circuitry. As mentioned, a good piece of equipment with adequate power supply is really all that's needed. You have the dedicated line, which is a good move.
If you're bent on having more audiophool stuff, there's AC regen or Audioquest Niagqra PLC's. Both get favorable reviews.
PL HP user/PS Audio PP.
The PL is good enough to not need any of that stuff, but alas, this is the hobby.