Just one E-Mat over the main power panel greatly improves both picture and sound. A mid-fi Yamaha CR620 receiver hooked up to the TV output (good cabling though) and a pair of ADS L620 speakers with one E-Mat resulted in deeper, more detailed bass, smoother mids and highs, more dynamic and lower apparent distortion/clearer sound ("blacker backgrounds"). So, if I were only able to buy one E-Mat, I’d place it on the main power panel.
For some reason, despite using 12 E-Mats, 3 on isolation transformer, 2 on subpanel, 3 under pre-amp/phono and 3 under CD player, the two monoblock tube amps did not have an effect. Maybe I needed more than 2. Also, 9 E-Mats are incorrectly placed with the printed side away from the device. It appears to work just fine wrongly placed. Can PPT let me know if after 3 months, if it matters or not?