The condition is not ideal but is modelled after real world conditions, digit-life said that themselves, not me.
Yes the attenuation is higher in high end and lower end, but it is in orders of < 1db in short runs.
And then, I must say again, there is
no way the extension can improve unless the efficiency is improved. The reason why at the same input power level, the sound output is higher, is because more power is reaching the sats, and hence it proves the point that efficiency actually increased.
Then your "theory" of improving the extension by 5db.

+3db is caused by doubling of power, +6db is 4X power. Improvement of 5db is as good as feeding 4X power to the frequency it is improved on.
So your miracle cable actually has 400% efficiency increase!

Think again.
As I've said, there will be improvements, but it is never as great as you have
advertised. And the improvements are mainly dues to better shielding, smoother flow of electrons through the wires to maintain the integrity of the in and out signals. The respose will be more linear and more responsive. The improvement is SPL, efficiency, depth, is not the greatest part.