Grannyring.
I have 7 ecards total and one mat.
The mat is on the Inside of main breaker door as posts suggest that is most effective place to start.
Ecards.
1 on Brooklyn DAC.
1 on Bluesound vault2 music server
1 on Goldnote phono stage.
2 on Equicore 1800 power conditioner
2 on Ayre ax7e integrated.
Out of those card placements only the Ayre coukd be exchanged for a full mat due to size of other components.
To my ears and in my system, it reduced background noise substantially even over what the blue fuses and blue duplex achieved.
To me they seem to have had most effect on instruments like piano and acoustic guitar. Appears to be more air and separation on individual notes. Hard to describe but I can certainly tell a change.
Now they have only been in place 1 week so expecting more.
