Schumann Resonator

Sure, you're welcome. 

@mapman  The Fourier series theory stands behind all of electromagnetism. 
The em wave emitted eventually by way of speaker transducer, becomes a sound wave. The cart before the horse scenario. The reason the Schumann frequency affects you, and all human physiology is because the frequency induces a calming, relaxed, yet alert and focused influence.
It is a theta frequency (7-12 Hz).
The idea has nothing to do with sound.
IT has everything to do with the manipulation of e signals that become sound waves.
That's what amps and speakers do.
There is no rational explanation out there that connects the dots.
Again: square wave, Fourier harmonic series, and resonance. All supported by laws of physics, which includes the science of sound. Get it?

I enjoyed reading through most of this thread, especially the explanations posited concerning the earth's frequency and dither. Very entertaining.

@bhvf  I understand your frustration and lack of any response offering a rational explanation.
@ps Ditto.
I can tell you that I have been working in the area of resonance and resonators for a long time and it took a longer time to discover a rational explanation as to why the Schumann resonance devices work to affect audio systems and signals.
The idea is not rocket science, in fact it's pretty elementary physics and electrical theory.
The frequency must be a low em frequency. It can be as low as 8 Hz or even lower. Google ELF or ULF in the frequency spectrum. 

The frequency generated is a square wave. Not a sine wave.

Joseph Fourier, the eminent 18th century physicist made the discovery that square waves are comprised of a series of harmonically related sine waves of various phases (cosines too) from the fundamental out to infinity. The good news is that as you sum the harmonics up the frequency band the amplitude of each subsequent frequency decreases in a logarithmic way.
Every Schumann device that I am aware of, generates a square wave at 7 - 8 Hz or so.
But the question is how does that affect audio signals?
The answer lies in resonance.
Just like a tuning fork, when the frequency of the fork comes into contact with another thing that has the same resonant frequency then that thing is going to vibrate or gain energy from the activating or stimulus energy signal. So, the low frequency square wave with its underlying sine wave harmonic structure interacts with complex audio signals comprised of  sines and various wave forms that can possibly be described under the sun, mathematically (i.e. calculus).
This interaction activates resonances throughout the audio spectrum depending on the activating or driving signal (Schumann) and the audio signal. There is more energy from the resonance happening at the lower frequencies than at the higher frequencies due to the higher amplitude of the early harmonics. Less energy at higher frequencies also assures a more musical affect.
The energy change can be easily measured with a sound level dB meter aimed at the speakers and can be seen on a scope or spectrum analyzer.

To sum up, a low frequency square wave unleashes a harmonic series that when introduced into an audio system, interacts with like frequency signals,produces resonances or an increase in energy or amplitude of those audio signals. 
Greater S/N occurs along with increased dynamic range to the sound.

Btw, there is a brand that promotes the idea and that is ADD-Powr.

I speculate that DACs can be improved because the resonances may influence the dither in a way to make "uncertainty" more certain.
That is to say the converter's resolution improves. Bits that were in the "gray" area are now defined to be a "0" or a "1". What was unclear in the data now becomes clear and strengthened after applying resonance.

@sokogear  Get a dB meter.
Play pink noise through your system at a level to read at about -50 or -60 dB. Use a fixed position for your meter. Turn on the Schumann device.
Read the meter, It should increase by a 1/4 to a 1/2 dB. .
A small change but still significant. Any fractional dB increase is still a lot of energy.

This is not about faith. It is simple and logical.

And yes, there is a rational explanation out there that connects the dots!

@sokeogear -
I said that I have measured  between 0.25 and 0.50 dB increase, sometimes more. Take my word for it. Also, the more harmonic resonators are active in the system listening area the greater is the increase in harmonic energy. This correlates to an increase in the S/N or signal-to-noise ratio as well.

I am not concerned with any other accessories or tweaks.

@djones    "Where can I find some scientific papers that back up this claim?"
Google search for brain wave frequencies - alpha, beta, theta.
@sokogear   Go get yourself an oscilloscope, open up the device, and you will measure the frequency. I guarantee that it will be a square wave 7 - 8 Hz. An EMF meter should measure ULF (ultra low frequency) placed over the device. Get a sound level meter. Play a CD of pink/white noise, whatever, through your system and point the meter to the speakers from your listening position.
Measure. Power on the Schumann resonator. Repeat the measurement. Any change that occurs is due to the harmonic series derived from the Schumann square wave frequency resonating with the pink/white noise CD signals.You will hear it - the increase in amplitude. And the dB meter doesn't lie.
I have done this simple test. It verifies what your ears tell you - that the sound pressure level got stronger or the sound got LOUDER! Anyone can do this. Just leave out the bias and bring in intellectual honesty.
 

@mapman  The Fourier series theory stands behind all of electromagnetism.
The em wave emitted eventually by way of speaker transducer, becomes a sound wave. The cart before the horse scenario. The reason the Schumann frequency affects you, and all human physiology is because the frequency induces a calming, relaxed, yet alert and focused influence.
It is a theta frequency (7-12 Hz).
The idea has nothing to do with sound.
IT has everything to do with the manipulation of e signals that become sound waves.
That's what amps and speakers do.

Again: square wave, Fourier harmonic series, and resonance. All supported by laws of physics, which includes the science of sound. Get it?

Delete previous sentence  " There is no rational explanation out there that connects the dots."  That was not my comment! My bad!