Not sure for power conditioner my amp or not.

I feel my amp sounds better with the power conditioner as well as the picture on my television..

Since my Onkyo HT drives all the video probably best to leave it on Power Conditioner and use the other outlet for tube Pre-Amp.

In South Florida we have a love of air conditioners cycling on and off and it causes fluctuations in the power supply.  I found that my tube amplifiers were regularly needing to be re-biased.  Since incorporating a power conditioner, the amps have stabilized to the point where re-bias in almost never needed.  The amps always sounded good, I can't say that power conditioners have done much in that regard.  I have tried Niagra and first P10 and now P20.  All with similar results.  Currently using PS Audio P20.  I did read the detailed report that these things do nothing.  I believe that is true if the power coming into the wall is good, consistent etc.  They are more necessary in localities where the power fluctuates, is dirty and so forth.

I would test it your self giving each trial a week before deciding

Since OP’s amp uses an EI power transformer which does isolation already, adding a separate isolation transformer may not give any benefit.

However, if the isolation transformer is wired in balanced manner, then it can help.

My house power is generally very good. I can watch with my "sense" power meter installed. I also added the Zero Surge and connected my Tube Amp and Tube Pre Amp into the Zero Surge. I plugged everything else into the Torus TOT MAX conditioner. I ended up with adding a whole house surge just in case. I wouldn't have done that, but I also was installing my generator switching panel. I figured if I was already having the walls open I might as well add the whole house surge. Everything is fine and I appreciate all the help from everyone!! Seriously, it was an informative thread for me. Thanks, Scott 

My house power is very good until it's not. 🤣

I live in the South where we are prone to severe lightning storms, though not quite as bad as Florida.  There is no way I run my gear without a top notch surge protector in line with it.  I also use a whole house surge protector as well. 

Plus, my experience having been in electrically noisy apartments is that my gear sounds better with a good conditioner than without it.

You can read more about my thoughts here:

https://pqltd.blogspot.com/2023/10/time-for-new-surge-suppression.html

Nice write up Erik, I have the Zero Surge as mentioned and I have an Eaton Ultra whole house surge. I can't really change out my Eaton electrical panels. For my Network/NAS I use a "clean sinewave" APC UPS. The ones used for servers in data centers that won't even turn on, if the power isn't clean enough. No wall warts, all LPS signature series from Lab Swagman. I can't afford a PS Audio P15 or P20. 

My Primaluna EVO 400 pre and power amps are plugged directly into the Hubbel wall outlets dedicated line. Since I don't leave these tube amps on 24/7 it is easy to just leave them unplugged when not in use and when I am not around to monitor lightning storms.

The CD transport and DAC are left on all the time and plugged into a Shunyata Hydra 4. These two front end components are also fitted with DIY ground boxes via RCA component connection (ie "signal grounds.")

This has been a very satisfactory arrangement.

Nice! I should just unplug the Zero Surge when I am out of the house. It would be easy enough to do.

The Primaluna's are tube amps which explains why I don't or can't just leave them on all the time. Were these solid state amps I would want them on 24/7 to keep them warmed up. The CD transport and DAC are best left on all the time which is why I keep them on surge protection.

I have a tube DAC and tube phono pre-amp, so I turn them all off.

If I lived in a location with lightening I would probably install someting like this on the power to my equipment.

The problem around here is you don't always know when lightning will happen in advance, and certainly don't' know a transformer just got hit by a car.  I mean, sure, when  a big storm rolls around I turn my conditioners off and sometimes even the breaker, but lots of times lightning has come out of nowhere at 3 AM around here. 

One of the stupid surge damages I used to suffer from was WIND storms taking out my DirecTV.  Apparently the excess wind would deposit excess electrons on the antenna surface and ZAP!  Out goes my satellite receiver.  Good to have high quality coax protection as well.