The Entech line tester is a very basic unit and fairly non specific.
It has both audible and visual references to allow you to both hear/see any changes.
As you have indicated, your power conditioner did reduce noise when tested by the Entech.
So, it is doing something. Just not sure what and to what degree. A lab quality meter or a scope can show some more detail on what is happening on your line.
You stated that your friends meter was for EMI. Anything else?
There are many variables that affect the quality of the AC produced.
Many manufacturers attack the problem in different ways and with varying degrees of success.
Did your power conditioner help the sound of your system? That's the bottom line.
There is always something better, but what do you really need?
I have the Alpha, but according to Carlin Gabriel, it is too restricted in bandwidth.
None of them is a professional tool and a complete meter. They work in a different bandwitch (one may show more of the low freq noise and the other more of the ultrasonic noise) so their results may differ. It is best to use both to get the most complete reading.
I recall Caelin Gabriel (Shunyata) said the narrower band the Entech measures is more appropriate to the noise which effects actual audio sound quality. It picks up AM radio loud and clear at our place.
Interestingly, we can sometimes hear radio broadcasts late at night without any receiving device other than our ears/brain. It sounds bizarre, but it's pretty common.
Fluke 199 scope meter and also a Power Logic Ion 7650. You need both. Find them used on ebay. The 7650 goes to 2,5 Ghz. That is well beyond and Mhz range.
As I said on other thread, what are you going to do with the info. The Ion will tell you just how much noise you have, but its not going to tell you how to fix it.
My friends at Schneider Electric use these 2 tools to diagnose noise from industrial Freq Drives and other noisy equipment. They then build filters to bock the noise from polluting the surrounding facility. They are very accurate tools.
I misspoke - the Alpha has a wider bandwidth but not the best frequency band.
Harmful to sound quality.