Doug Schroeder Method, Double ic

Oddly what you are doing makes sense to a degree.  I know nothing about the interactions of cables and gear.  As in why it happens.  Only a glossy idea of why it occurs.  Ok, I'm uneducated.  Now that that is clarified, I have made the following observations.  I have connected some interconnects between my DAC and preamp, as well as between my Preamp and amp.
One set of interconnects is the Inakustik NF2404
One set is the Genesis by Gary Ko
The other is an inexpensive coax interconnect.

Here is what I observed. 
Between the DAC and the preamp the coax and the Inakustik are hard to tell apart. The Inakustik is better, but not by much. The Genesis is an OMG that is great.  The world opens up.  I use the Genesis there.

Between the preamp and amp the coax, Inakustik and Genesis are hard to tell apart but they are different.  The Genesis is a little thin, so I keep it where it excels.  The Inakustik is more fleshed out and full.  Very clear and accurate.  Pretty neutral but very full.  I like that so it stays between the preamp and amp.   The coax is just there.  Nothing special but pretty darn good for $250.  It is not as clear as either the Genesis or Inakustik.  There is some haze and cloudiness to it.  It is not in use.  

The Genesis is designed around 2 wires on the positive and 1 on the negative. Kind of like your doubling up of interconnects.  Different but similar.  The Inakustik is 2 wires in an air dielectric spread very far apart.  About an inch plus. Totally different geometry.  I am sure their inductance, reactance and capacitance and radically different.  I assume that is why the results based upon where they were used if quite different.  If I were to do a review on either the Genesis or Inakustik and I based the finding on one topology alone, I might find either cable inferior.  If I used the cable in another area, I might find it heavens sent.  Interconnects are tricky business.  It's hard to tell if you are going to get the same results as someone else who raved about them.  From what you are all saying and the links included say, it seems cables are very system dependent.  

Thanks for validating this idea for me.  I got in a fight with one vendor over this very issue and feelings were hurt.  Now I  can't get any more cables at discounted pricing.  I'm just another chump having to pay list price. For that brand at least.  Owe Well.  I really don't need anymore unless I purchase a tape machine.
Rex

What do you think is being filtered that is improving the sound?  What other ways do you think you could achieve the same ends?

Celander,  How do you get extra bandwidth.  You lowered the resistance with parallel conductors and upped the capacitance and induction.  I don't see any reason for the bandwidth to change just because those changed..  I get the DAC and preamp are reacting to the change in current, but I don't see that raising bandwidth.  

Unless the conclusion was changing those three electrical components resulted in a cleaner signal with less noise allowing a component to operate more efficiently and more readily reproduce higher frequencies.  But that is filtering out noise to allow better operating parameters.

What is it that you see in changing the induction capacitance and resistance that would make frequency change.

Ok, I re-read it.  I gather the resistance went up, not down.  And a warning that amps may not like this.  I still see nothing talking about frequency extension or any engineering theories on how changing the electrical values passing the signal would benefit frequency extension.  

If such a simple concept as increasing mass would increased frequency then more designers would use it. I know they alter mass with speaker cables. Almost every manufacturer charges more for the better speaker cables which all seem to have heavier gauge wire. In my own personal conversations with cable manufacturers they say purity of material spacing from one another as well as shielding, construction insulation etc are the critical component to obtaining optimum sound. I doubt they would all miss added mass and not focus on that if it was relevant.

I am in no way saying Schroeder did not obtain positive results. It seems he and others have experimented with a topology and antidotal evidence is showing some benefits in their systems.  I am just wondering what the real reason for the results is. Can Improvement of the signal resulting in higher frequencies being reproduce by the amp be done in a more efficient and or cost-effective manner. Doubling up interconnect which are already expensive is pretty cost prohibitive. Especially when you need to do it between a phono, a DAC,  a CD a tape machine excetera. That's a whole lot of cable and additional Hydra head behind your gear.