Power Conditioners

You do NOT need them, unless you live somewhere with a lot of lightning strikes. Other than that, there is no need. The filtering in the PSU of your devices are more than adequate. The rest is mostly snake oil or the improvement is so insignificant, it is not worth the expense.

If you have hum or noise issues, they are typically due to other reasons.  Those typically occur when you connect 3 pronged (with an earth connection) plugs to DIFFERENT outlets.  The miniscule potential difference which exists between the different earth points are what causes hum issues (earth loop).  Make sure that ALL your 3 pronged plugs connect to the SAME outlet, making a star connection.

Bull pucky. It's not snake oil, no matter how often someone gets up on their soapbox and yells at passerbys.

 I've measured the AC over the course of many days, all day long and it never varied more than +/-2 volts.

No lightning strikes here either.  All gear is built to a price point and based on tech from many decades ago. I thought everything was hunky dory until I got my Niagara 1200. It was no contest concerning the difference.

To infer that all equipment out there is improperly designed and built i(if you end up hearing a difference) s silly and misleading.

Here, read this from John Atkinson of Stereophile (the king of measurements and always quoted by the naysayers as some kind of justification to rely on measurements only)
https://www.stereophile.com/content/spectral-x-contamination-problems-op-amp-chips

The article is about op-amp chips but goes into some depth on the lack of proper measurements and the equipment needed for them. Small things have a very large effect.

All the best,
Nonoise

again. Snake oil. 99% of electronics will already rectify/filter 99% of the noise out of the PSU dc lines reducing down to a miniscule ripple. You will not hear any difference.

İf you are hearing a difference, you must live somewhere where your power company should be taken to court for not being able to provide even the basic service. 

So you do have a noise issue? Is that correct, noise issues that you can hear? Usually ground loops and routing. I've heard some NOISY systems behind lazy cable routing.  A wall wart won't make noise go away when it's a routing issue. Though I've seen a LOT of folks try.. LOL

We never had lightning strikes closer than 50 miles from my home, either until a month ago and lightning stuck a house two block away. Lightning strikes on the mountain, not uncommon. That same round caused some serious brown outs, black outs, and then surges, coming back on line.

It’s your equipment, me, it’s safety first, I protect equipment by maintaining the voltage, 120 on the button. I’ve never had a SQ issue, noise issue, or loosing expensive equipment because a LACK of protection. I just don’t do it. There is NO reason to lose anything..
I’m a mechanic, I stay out of trouble, NOT get out of trouble...

You keep saying "in phase" do you mean on the same rail at the main, your loosing me here. ALL on the same 120 vac rail? There are two 120s and 240 vac between the two. 240 vac single phase.

Regards

You keep saying "in phase" do you mean on the same rail at the main

Google it my friend... maybe it’s different in America?