MOV based surge arrestors don't merely divert current to the ground and neutral conductors (circuits). They dissipate the energy of the surge pulse in the MOV assemblies. Now the ground or neutral conductors do carry current during these surges but, this should cause no concern assuming your house wiring is in accordance with the safety standards and codes designated by the NFPA. These shunt type MOV units often include a one or two stage RFI filter as standard also. And, they offer minimum series impedance, certainly an advantage when feeding a power amplifier.
Nevertheless, the brick wall filters are good also. But, I do question their ability to properly clamp a surge voltage on the hot conductor if no current flows into the gound. Normally surge pulses appear between hot and ground or, neutral and ground. If these units do not pass current to on the ground conductor then how do they limit the peak voltage appearing on the hot conductor during a hot to ground surge(especially slow rising surge)? Remember an inductor does not offer much impedance to a slow rising waveform - such as when your utility power merely fluctuates due to system instability/oscillations, etc. when the grid is subjected to disturbances such as blowing a throwout on the pole. Also, these inductor type filters generally exhibit a significant series impedance which may hinder the stiffness of a power amplifier. But this should not really be a major concern because supply impedance is often overplayed in the audio hyped marketplace.
Nevertheless, the brick wall filters are good also. But, I do question their ability to properly clamp a surge voltage on the hot conductor if no current flows into the gound. Normally surge pulses appear between hot and ground or, neutral and ground. If these units do not pass current to on the ground conductor then how do they limit the peak voltage appearing on the hot conductor during a hot to ground surge(especially slow rising surge)? Remember an inductor does not offer much impedance to a slow rising waveform - such as when your utility power merely fluctuates due to system instability/oscillations, etc. when the grid is subjected to disturbances such as blowing a throwout on the pole. Also, these inductor type filters generally exhibit a significant series impedance which may hinder the stiffness of a power amplifier. But this should not really be a major concern because supply impedance is often overplayed in the audio hyped marketplace.