ACTUAL MUSICAL SOUND VS. MEASUREMENTS

@calvinj OP - if, and only if change can at least theoretically affect the sound.

Change is Sun position in the galaxy is also a change. Neutrinos passing by have gravitational field that affect human brain. It is 10 in minus 100 power, but some may claim they feel it.

@spenav - there is nothing "unknown" in USB or Ethernet protocol. Your signed mortgage documents do not change with time and ripped music does not lose any bits sitting on a hard drive :-) Are you concerned that music file may change when you copy it between folders?

Basic engineering. When you are buying a car or a home, do you look for quality construction and actual measured performance. Or do you trust tales of "italian soul"? Same thing.

Poorly designer equipment will still sound great with some music in some room. Say, your room has resonances. Well, speaker that dips at those frequencies will sound great to you. Flat speaker will sound horrible. So there. Equipment that measures oddly is just and equalizer.

Why, cables will greatly affect old type tube equipment where input or output impedance is reactive. Poorly designed power supplies will be sensitive to power cables.

Now, Ethernet cables do not matter. Seriously. :-)

@calvinj - totally. All I am saying, poorly measuring speaker is like EQ and may sound great with some recording and some rooms. Completely flat speaker sounds good in properly treated room. My setup is NOT flat intentionally, it is set up to MY taste. But I did measure it :-)

Real differences are always measurable. Otherwise it is not science but faith.

@toddalin - pretty easily by waterfall and some calculations of the sound field distribution across the room. 

@calvinj OP - have you noticed sound changes with the amount of consumed adult beverages? So there :-) Also, never underestimate how furniture, rearranged by your SO affects the sound!

@toddalin - It can be done, but who exactly needs it - as in who would pay for it. Audiophile community does not care. Speaker measurements exists because they are used in professional audio where no one "just trust their ears". Now, imaging is a sound field distribution over time. So it is minimum 6-dimensional measurement that is hard to visualize. 3 space variables, time, then as a minimum - frequency and amplitude at a given point in space. More realistically several frequency variables (coefficients in frequency domain after Fourier transform). So we are facing many, many variables. Hard to visualize, but it can be measured and compared. Will require several microphones at different points, measurements of the room itself and a bunch of math to extrapolate the complete field.