Do equipment stands have an impact on electronics?


Mechanical grounding or isolation from vibration has been a hot topic as of late.  Many know from experience that footers, stands and other vibration technologies impact things that vibrate a lot like speakers, subs or even listening rooms (my recent experience with an "Energy room").  The question is does it have merit when it comes to electronics and if so why?  Are there plausible explanations for their effect on electronics or suggested measurement paradigms to document such an effect?
agear
agear, I’m glad you asked about harmonics in the context of music. Before I made my last post above I checked my Musical Notes chart to see how out of tune various harmonics are. Here’s the chart which shows a tempered scale, though that’s what everyone plays so those are the appropriate frequencies to consider:

http://ethanwiner.com/misc-content/notefreq.gif

This analysis is easy if you use A at 110 Hz as a starting point because you can easily do the math in your head:

2nd harmonic: 220 Hz
3rd harmonic: 330 Hz
4th harmonic: 440 Hz
5th harmonic: 550 Hz
6th harmonic: 660 Hz
7th harmonic: 770 Hz
8th harmonic: 880 Hz
9th harmonic: 990 Hz

So looking at my chart it’s clear that the 2nd, 4th, and 8th harmonics are all perfectly in tune, and thus "consonant" (versus dissonant) with an A note because they’re perfect octaves. The 3rd harmonic at 330 Hz is very close to an E, which is in the key of A major and A minor, so we’re good there too!

Next is the 5th harmonic at 550 Hz. That’s a few Hz flat of a C# which is the major note in an A major scale. So that will sound a little off if it’s loud enough to hear. But what if the music is in the key of A minor? Now that 550 Hz is way out of tune because the deciding note for minor is the C natural at 523 Hz. Fortunately, harmonics usually (though not always) decline in level as you go higher, so with normal causes of distortion the 5th harmonic is pretty soft in any competent audio gear.

And now we get to the famous 7th harmonic, or is that infamous? LOL. Here 770 Hz falls between an F# and a G, being out of tune with both. So yeah, it would be a problem if it were loud enough to hear. But again, with competent gear it will be way down by the noise floor and thus inaudible due to both its low level and masking by the rest of the music. The claim that high-order distortion components are somehow magically audible even when they’re incredibly soft is itself incredible. And as we all know, the more outrageous the claim, the more compelling must be the proof. Though at this point I’d settle for even minimal proof, as opposed to "because John Curl said so." :->)

Of course, as I have pointed out literally dozens of times in my various articles and videos, whenever you have harmonic distortion (THD) you also have similar amounts of IM distortion (IMD). And IM distortion is usually out of tune with the music, and so is much more audible and damaging than most forms of THD including the 7th harmonic. Chasing increasing small amounts of high-order THD in the presence of large quantities of IMD is like chasing unicorns.
whenever you have harmonic distortion (THD) you also have similar amounts of IM distortion (IMD).
This statement is misleading. You can have a fair amount of THD and still have relatively low IMD figures. This is however a very common saw and often it **happens** to be true; its just not true 100% of the time. 

And IM distortion is usually out of tune with the music, and so is much more audible and damaging than most forms of THD including the 7th harmonic.
This statement is true.

Chasing increasing small amounts of high-order THD in the presence of large quantities of IMD is like chasing unicorns.

The meaning here is unclear.
This whole thread has taken a nasty and totally unnecessary turn. In the first place ever since the bullet headed amplifier reviewer from Audio Review opined that all amplifiers that measure about the same sound the same, audiophiles who actually can hear have laughed at anyone who demands proof or measurements. A lot of you young whipper snappers are too young to remember the big solid state amp vs tube amp debate from the 80s. But noone could explain completely why a solid state amp with vanishingly low 0.0005% THD could sound SO %€$@! BAD relative to a reasonably good tube amp with 0.05% THD, which according my calculations is TWO ORDERS of magnitude - or for those technically challenged - 100 TIMES HIGHER than the solid state amp’s THD. Hel-loo!
Crown amps of the early 70s had 60db of negative feedback and no distortion.??vs a Marantz 8b that had over 1 % thd..but you could listen into it all nite long. Tom
Ralph said: " You can have a fair amount of THD and still have relatively low IMD figures."

I doubt it, though I'll be glad to be proven wrong!