Seeking power conditioner recommendations / hum elimination

It's extremely unlikely that anything in that price range will deal with the hum.  In fact, it's possible no after-market product will eliminate the hum.  The first thing to do is to discover exactly where it's coming from and what it causing it.  There are two basic causes and other possible ones.  I recommend you search "hum" and "buzz" on pre-existing threads.  You will find lots of references.  Some people go to heroic lengths to eliminate hum and never achieve it.  Sorry: reality-check.

I’ve NEVER had noise that wasn’t fixable. It’s usually routing.
Cables too close to each other.

PC are a big source of noise to close to IC, ground loops,
 and NOT sharing a common power outlet.

I add a maintainer, cleaner, for just that.
Maintain 120 and clean it up a bit.
HF issues for me, with dirty VAC.. Ear bleeding, BOIL..

I fix the noise first WITHOUT a conditioner attached.

My 2 pennies...

Regards

I have a mild hum originating from the AMP2 that I can’t seem to eliminate.

Wait, you mean it's physically humming, or you have diagnosed it to be the amp by disconnecting everything else?

Start here.
https://www.psaudio.com/ps_how/how-to-find-and-fix-hum-extended/

The noise is coming from the speakers, not a piece of equipment?

60hz or 120hz, one is cable routing and so it the other, kinda.

For a test, remove the ground with a cheater plug.  If it goes away...

Hook ground between equipment.
    
60hz stuff usually YoYo's, moving the cables raises and lowers the noise floor.

Again usually routing, sometimes a voltage difference.. The ground wire will tell you that.. Couple of test leads, hook between equipment. 15 minutes, you aught to be able to fix it...

If wires aren't touching, they usually don't make noise. But terminal ends can get noisy too, plug and unplug, to clean.. Normally though it's intermittent. 

You'll get it..

Regards

Thanks all, some responses from me...
My father-in-law calls it a "60 cycle hum", so I’ll go with 60 hz. If I power up all gear except for the amp I don’t get a hum. Powering on the amp triggers the hum (heard through the speakers, yes). I have noticed that I can increase/decrease the hum by moving cables around, but it never quite disappears. I tried a cheater and the hum remained.

Another tidbit I should share, LED lighting in this room flickers a tad bit and also has a buzz/hum, as does the lighting in the room on the floor just above it. Even though I have a dedicated line, I'm assuming it's sharing the same source/electrical box as our problem area, i.e. the same zone.  We’ve been meaning to have an electrician take a look at that side of the house for issues when we have time.  I don't know if that sheds more light on the situation.

In the meantime I’ll try those suggestions. Thanks much!

 I have noticed that I can increase/decrease the hum by moving cables around, but it never quite disappears. I tried a cheater and the hum remained.

Now zero in where that happens. Spread the wires apart in that area.

Cross at a 90 if you have to cross, and keep distance between all cables shielded or not.  

It sure sounds like classic routing issue to me...Easy peasy...

Regards

If LED lights are buzzing that could mean those lights are on a dimmer made for incandescent bulbs. Those triac dimmers can put electromagnetic interference on your circuits causing both the audio ground loops and the lights buzzing. If they are not on a dimmer then you have EM sources from somewhere else. First things I would check is the house panel ground ( not loose or corroded) and the wiring in the panel are tight to the breakers, neutral and ground bars. That is a necessary first step before you start the ground loop hunt.

@atticus-xi

Even though I have a dedicated line, I'm assuming it's sharing the same source/electrical box as our problem area, i.e. the same zone.

then its not a dedicated line.        a dedicated ac line would have its own breaker and the only thing on that line would be the system.

EBTECH HUM X  ELIMINATOR.  WORKS LIKE MAGIC

https://www.amazon.com/Ebtech-Hum-Ground-Voltage-Filter/dp/B0002E4YI8

I made this homemade version using this Video and it worked.I had issues with my Schiit Audio Freya
https://www.youtube.com/watch?v=CuvDMjxhE68

another video for homemade Hum eliminator
https://www.youtube.com/watch?v=qNQX8jyxRrs

After you have fixed the emf noise / interference issues, and have installed a proper ground, then you will be surprised at what the ADD-Powr Sorcer or Wizard will do for your system.
These products won't eliminate "hum" but they will have you humming along to your favorite tunes!

One thing you can do is disconnect all interconnect cables and power cords.  Then start with your amp.  Power on the AMP2 with only speaker cables connected (no RCA/XLR connections from preamp).  If you have a buzz at this point, then something is wrong with AMP2 and it needs to be repaired (likely a dried out power supply capacitor). 

Then connect in the Krell KSL preamp.  Make sure there are NO cable connections to any sources, such as turntable/DAC/etc.  Power on the KSL and see if you get the hum.  Then add source devices one at a time and power them up and select each one as an input for the preamp.  This may help determine if a specific source/preamp is causing a ground loop.

Sometimes certain products combined with other certain products will create a ground loop hum.  I had a severe ground loop hum when using Parasound amps in my system with a Krell processor.  This ground-loop hum did not exist with other types of amps, only Parasound.  The Parasound amps were totally fine in other systems.  I did try the Ebtech Hum X filter, but it did absolutely nothing.  I ended up selling the Parasound amps because the sonic signature was not my taste.

That being said, I have read positive things about the Granite Audio "Ground Zero" system.  It's expensive, but it's supposed to equalize the impedance of the ground point of your different devices and kill the ground loop hum.  $660 is a lot of money, but