I am panning to upgrade my Panamax 5300. Recommendations?

damn, the Niagra is a major jump from what you are currently using ($6k+).

I had similar voltage issues, not sure the Niagra will help with this. It will cut off to protect your equipment just like your Panamax unit. That is the job is needs to do.

I have a lot of tubes in my system, so sensitive to voltage swings. When I first built my system, I was blowing rectifier tubes. Did some investigation and found that I had a swing in voltage from 118v in the mornings to 127v at night. I called the power company and they said that this type of swing is within their spec and they can't do anything about it. 

More research and a couple of rectifier tubes later I installed two variac transformers. These units are around $200 depending on what you get and I use them to monitor and dial down the voltage to the system to keep it in the range my equipment is safe using. It's not a set it and forget it device, it can only raise or lower the current coming out of the unit to your equipment, so it depends on what voltage is coming out of your wall. I usually set it to 116v and make sure I read it before powering up the equipment. (I think I have it dialed in now and really don't have to touch it anymore, mostly listen to the system after 5:00 pm so it's set for that voltage). These things have saved my sanity. I got ones with digital readouts so it's just a glance at the unit to see if I'm safe to turn on my stuff.

@katzenjammer27 Thanks for the detailed information. The only tube equipment I have is the LTA preamp, but I am concerned for all of it. I will look into the variac transformers, although I would prefer a set it an forget it solution.

The problem with the Panamax is that after it shuts down several times the feature weakens until it no longer works. Over the past 20 years is may have shut down half a dozen times prior to the past week. My electrician recommended we leave the system off until the dedicated 20 amp line is in, and we receive confirmation from our local power coop regarding the swings in voltage.

@hilde45 To answer your question, I don't know how to or or have the tools to measure the quality of the power coming into my system.  Over many, many years I've decided I don't care about measurements and specs because I can't hear them.  I've been fooled too many times going by specs and measurements expecting something and not hearing it.  My evaluation method is by ear only.  So in that spirit, I spent an hour last night to see if the Niagara 5000 was actually doing anything.  I took my large amp off the PC and plugged it directly into a 20amp outlet.  I left the pre, streamer (N20 like the OP), and DAC feeding off the Niagara and only changed the one variable (amp).  To simplify this test I used streaming only since it seems that is the OPs preference.

What I found with no conditioning to the amp is that the sound stage actually got wider and taller and the individual instruments and voices gained in size.  While doing this the soundstage got less deep.  In some rock tracks it sounded like the vocalist was sitting on the drum riser rather than at the front of the stage.  Also, while the things got bigger side to side they lost some focus esp. with acoustic instruments.  They were larger but less lifelike and didn't have the convincing texture that the Niagara provided. 

All in all with the amp plugged directly into the 20amp circuit I felt like my system took a step in the wrong direction.  The presentation seemed less real, less focused and less satisfying.  Those are my amateur findings and your mileage may vary. 

I hope this info is in some way useful. 

Side note, I didn't look at the Niagara 7000 because I felt like I didn't need the additional headroom.  I took the money difference between the 5000 and 7000 and invested in a better power cord and I think that was the right move.  Good luck and cheers.