...And add about 5 meters of pure lead over and below the house to protect from solar radiation, neutrino, gamma rays from deep space, and of course, throw away your latest I-phone and wireless router and laptop as possible sources of RF interference... Then check the purity of the solder used inside your equipment. If not pure enough, replace with 24 carat gold. Then check the purity of all the capacitors... Maybe some of them not strictly produced to specification. Make sure they are properly insulated against vibrations, because vibrations can make liquid separate from the PURE foil and electrolyte, and therefore it can change capacity of the given capacitors in certain range of pure frequencies being reproduced.. While at it, check the purity of the wire in the speaker drivers... If the crystalline structure of the copper wire is not perfect, maybe you have too much resistance at given frequency, which may induce non-linearity in frequency response...And also, one should check magnetic properties of the speaker drivers...because they are most important part of the sound repro chain... magnets can be finicky... Their magnetic field can get out of shape for many reasons... Purity of crystalline structure of the metal used as a base for the body of the driver ... Proximity of magnetic sources... that in turn can produce non-linearity in maximum excursion range of the speaker membrane... That would be catastrophic...Total loss of linearity in the carefully setup system... I wonder how many of you can hear that?
When all done, it should be nearly perfect.. except for neutrinos.. which can travel trough parsecs of lead. So, alas, no perfection is possible.. It is a non-zero mathematical possibility that one of them decides to react with a perfect setup of the cables in a most critical moment and ruin the perfect sound..
But, keep listening to experts...There is always hope...