Ac power bick wall filter?


How can i "eliminate" any frequency above say 70 cps from my power supply to stereo?
ptss
The only way to be even 99% sure of this is to use a power regenerator.  See PS Audio.

The next level below is an inductive low pass filter.  See ZeroSurge/Brickwall AC filters.




In the U.S., utilities regulate line frequency within a very tight tolerance - it's necessary to keep the electrical grid stable. Voltage is maintained to a much looser tolerance.