Line Conditioning and possible ground issues?

I did a panel upgrade a year ago and I think I heard an improvement of sound, I.E. a darker sound stage, the instruments clarity improved. The new panel had better earth grounding and a couple of connections to earth.

My power conditioners have always been PS audio, and I believe that no matter when it has no good grounding, the improvements are marginal at best

To avoid being held responsible I want to state my recommendations really simply.  From where the OP is his best solution is to hire a licensed electrician to check the wiring from the breakers to the receptacle and install a properly wired 3 prong outlet. 

This is what's going to be best for life safety and the safety of his equipment, and to ensure any surge protectors work completely correctly. 

Erik, you have the right answer. And I am planning on having a qualified Electrician look things over soon, and proceed as required in whatever logical manner.

Agree with @erik_squires.

A bit of an update for you to ponder over.

I got a Greenwave bundle a couple days ago, came with 2 Filters and a Noise Analyzer.  Did this because I was thinking the Entec Analyzer I have might've been faulty.  So, now comes Test #2. 

With no Greenwave Filters plugged in anywhere, I took a reading with the Greewave Analyzer first.  Plugged the Puritan PSM156 into the other Duplex Outlet. 

No change in readings either through the Duplex Outlet, or directly into any of the 6 PSM156's Power Outlets.  Zero change.

Then I plugged in one Greenwave Filter and the numbers, and the noise dropped considerably.  I don't have the numbers to quote offhand, but like an 85% or so reduction. 

I then added another Greenwave Filter to another outlet in the same room, and the noise dropped even further. 

Again with a couple different Outlet Testers, both showed correct phase and grounding.