I just read you're using the Siemens surge protector. No doubt that gives you peace of mind but be aware it is unable to stop all conducted electromagnetic disturbances. There are many different kinds besides surges and they include fast transients, bursts, slower oscillatory waves, voltage dips, short interruptions, voltage variations and steady-state low frequency (<150KHz) disturbances. I've also noticed Siemens doesn't describe the surge waveform and test methods (although I am sure that data is available if you ask). If you believe you are having "power quality" issues at your place, it may be worth talking with your utility to see what they might recommend and why. I had issues at my place a decade ago and after taking some measurements with equipment I borrowed from my work, I strongly suspected my pole-top transformer. I passed all my data to my utility and sure enough they replaced the transformer and all my problems disappeared.


House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated