In advance of my mains noise meter arriving I try out moving one of my Kemp filters

Three in place, all on the same circuit as the system, one on the left and two on the right of the system

Listen - good

Turn off socket on far right Kemp and move to kitchen, closest I can get to where power comes into the house

Play track again
Ears deceiving me ?
'Louder', background more forward into the mix, smoother sound, even easier on the ear

Swap back to start
Flatter sound, some detail, space and air lost

Subtle, but there, not night and day, more like 4pm today in bright sunshine and 5pm with the sun beginning to fade

Good result Mike, shame you can't get the Kemp with UK plug anymore, although l'm sure some type of adapter will exist.

Confirmation test with the golden eared one today

Kemp in the kitchen turned off
Play track, sounds wonderful
Kemp on
Play again. Harshness gone and seems louder

Same as yesterday and confirmed by the boss
"Golden sound"

What if ?

Spare Tacima available
Take to the kitchen and into the other socket of the double with the Kemp in

Wow. Sounds better again, not quite the step up the Kemp gave but noticeably better
If you look back up thread the Tacima doesn't measure well at all so what's going on there then ?

I have various around the house.
Will concentrate more in the kitchen

Excellent results Martin 👏. You touched on a subject l was discussing with Matt, the LHY meter is quite limited in its range, 300khz to 700khz. This lead me to look up the ifi AC purifier spec,sadly the only give away is a graph, and interestingly it looks like the ifi starts around 700khz and above, out of range of the meter,so you could use it before the other filters, however l get your point, there are better filters out there,l'm looking forward to my meter arriving, just wish it covered a wider bandwidth, still its good fun, and it will be interesting to hear if additional filters make a difference on my Puritans.

Not at all Martin,my point was about the Meter,it dosent cover the frequencies of the ifi,as l stated there are better filters,l understand your feelings on the noise,so l'm not sure if you understood.l was trying to point out the pit falls of the meter.Another example, and this is not based on any fact, let's say the Kemp filter is noisy at 150khz ,the LHY meter wouldn't pick it up.. so you would be trusting your ears and not the Meter, actually the LHY reads a very narrow frequency spectrum, that runs from the Top of Low Wave into halfway if the Medium Wave band, it could possibly add Radio signals into the noise readings,if your close to a Medium wave transmitter,l'm not trying to put a negative spin on it, just offering my years of experience within my hobby of Radio listening, you would be amazed at the similarities involved.

l understand your logic... But if you have already purchased a ifi, you could use first to kill off everything from 700khz, then use the kemp to clean the clean below 700Khz.
Personally l would take the LHY meter with a pinch of salt,a bit of fun,it covers such narrow frequency band, in reality it covers probably Less than 1% of the spectrum.
I understand your reasons, but know doubt if the LHY covered a wider frequency spectrum,it would show flaws with most filters at certains frequency points.

l guess it really depends on the source of the interference,as that will be personal to everyone,the only way we will ever know if the ifi does what it claims filter above 700khz and invest in some proper test gear,but we are moving into Tony territory really, if we could see a graphical view of all the frequencies, then we would have a definite answer.
lnterestingly and l haven't checked on Amazon, has the ifi had any positive reviews?

Excellent... And what's interesting that all the filters don't seem to kick in way after the 700khz range. Interestingly the ifi has less filtering rejection,so that backs MartinT findings and experiences,the ifi works, but just not as effective, plus it bangs out interference to the frequencies it's not trying to suppress, it just a case that the LHY have chosen a band that the filters don't cover, however fair play..if they hadn't chosen different frequencies to test,then MartinT wouldn't have picked up on this and apart from it not sounding as effective, we would be non of the wiser... Thanks for the link of the test,it answers a lot of questions...