"You can never measure the difference at this level. Even with the very
best 24bit/192 kHz equipment and the most modern method of analysis, you
are measuring with very, very elementary and crude waveforms which will
never simulate a complex musical waveform. Let's suppose that from the
factory the speakers look really flat, say +/- 1 dB (although this is
never the case). After even a thorough tweeking they will still look just
as flat but may sound much, much better. The improvement in this
theoretical scenario is not in the flatness of the curve but in the
preservation of the integrity of the signal getting to your ears. Many
speakers can also be hugely improved by optimizing the diffractive
properties of transmission, inside and outside of the cabinet."

There are a few expressed and implied strawman type arguments here, all of
which have been covered well on this ng before and need not be addressed.
If a few inches, 24?, of wire in the box makes such a difference, why
can't the several feet in the crossover and speaker coil simply continue
to overwhelm any very small subtraction to whatever "problem" replacing
the wire affords? If one can't measure any difference in the properties
of the wire, how does one know there is a difference to make it "sound
better"? How does one measure the integrity in a before and after wire
swap? If there is a wave, complex or not, shape change related to
integrity, how does one know it suffers in the absence of gear to measure
same? If in fact such cann't be measured, how does one know that the
existing wire in fact is not far superior to wave integrity then any
possible substitute? On what experience of measurement, at what ever bit
level and depth, can we even know in the first place or confirm anew that
wire does something to wave integrity; such that you can start with that
presumption on which to make deductions? The box shape effect on
difraction are well known, all such for the exact theoretical basis
confirmed by measurement.