best power conditioners under 4k

Whether you need a conditioner may depend on
where you live and the effect the grid has on your line voltage. It can be unstable and/or have noise. I live in a city and the power to my house is dirty. I’ve ruled out noise from appliances and devices inside the house since my electrician rewired my service panel plus installed a subpanel with two dedicated lines.

Adding a Core Power Equi=Core 1800 (balanced power) to my system lowered the noise floor significantly and improved the music presentation in every way.

Right. But not for the reasons you think. You're still getting noise from your appliances, and everything else for that matter. All that happened was you improved that one little thing.

Improved a major issue to the noise floor. I'm living in an old rowhome in an old neighborhood with shared lines, shared transformer and ungrounded houses.

Of course, appliances are adding noise; they're wired to the panel on both legs. Tweaks could be used here, but right now I'm satisfied with the improvement.