It appears to be fairly legit but there is a concern or two.
The signal going through induces a magnetic field onto the winding. There is no power going through the other winding.... This means it, within reason, should not induce any thing back to the original. However because it is being induced upon, and there is no way out, perhaps it gets fed back into the first winding.....
Thoughts on this..... The increase in impedence may not be real impedence.... This may be just extra power dispursion through magnetic fields, a possible cycle between them which ultimatly should bleed off via going through the speaker at say half power, 1/4 power... Do think of this as being in nano-second terms though.
That would not be the result in the amplifier having an easier time working with out such low impedence.... The speaker to it would appear to be possibly taking more power, but this would not result in an easier time for the amplifier; the amplifier would still be doing the same work.
Now being more resistive as the magnetic lines of flux going between the windings would provide some resistance, some increased impedence. This would make the load on the amplifier easier.... However in order for this to work you can pretty much assume the signal from the primary is going to the secondary and back, the induction causeing the increased impedence. If there is a bit of magnetic induction coming back from the seconday this could mean a miniture signal, possibly delayed causing a small smear of the original signal....
How small would this smear be? Well it could be enough to cause a pleasing warmth in midbass and very slightly taming of highs, yet nothing to noticable on the bass. It could also be so small you do not even notice it. Depending on the winding there is the possibility also that any signal re-introduced could be so far out of the 0-20khz range that it would be negligable, as it would be so small and not reproducable by the speaker or even very carriable by the material all the way to the speaker. I honestly highly doubt the possibility of him considering having the secondaries act in this manner.
Would I use this product? Yeah it probably works well enough that I would if I need it.... The price? Now that I am not entirely sure about being the most legit. I believe there is a slightly sacrafice in sound but it may not be one you can notice.
How would I make this better? Why not have the secondary winding come out of the transofrmer... That way you can attach it to an AC plug on the ground, the U shaped one, not the blades. Why do this? I figure perhaps the induced bit of signal would bleed out through the ground as opposed to back into the primary.
Am I an expert on any of this? Hell no but I do know a few things about transformers and electricity.
Overall this is a practicle but not perfect product. The only real discussion is the price and why he did not go for the AC plug bleed off. I could be more than wrong about the AC plug, and the other stuff.
Quality of binding posts? As long as the binding posts are higher resistance it will not be an issue. You would actually be better off using any thing not gold plated, not copper, and hopefully worse than brass for conducting. That would insure as little as possible passing through them. The alternative would be some copper, silver rhoadium coated Cardas binding posts. That makes the zero impedence box appealing as it appears to use just that.
The speaker cables and RCA by the same dude? Now that might be questionable? Those make look a little bit like a gimic. The zero autotransofrmers are some thing I can understand, the speaker cables with no information given, and just a bunch of spastic reviews....... I am not so sure about them. There is nothing given to really make me believe they are special in any way.
