Doug Schroeder Method, Double ic

Correct, larger gauge won’t get you what you are looking for. I tried a standard 12 gauge set vs the DS method with 16ga and the DS method with 16 gauge was certainly better in every way. 

I test and make cables daily. It is what I do. Yes, I test all manner of gauge, dialectic, twist, materials etc.., No, not just once or one combo.

It may be possible to find an outlier to my comment and in audio one must always leave the door of possibility open. I also know we all hear differently. My comment is based on my experiences, in general, with ICs. I did not take the time to post all my gauge testing in my post above.

Yes, the previous posts are in agreement with your comment about additional conductors being a good thing. This is a point of agreement. This is especially true when done in the DS arrangement.  However, if using only one positive and one negative individually insulated wire there is a point when the thicker gauge is no longer a benifit.  It actually becomes a sonic negative. I gave one example. 

Shotgun speaker cables has been around since the 1970’s. That’s not what the SM is about. If one wants to double up speaker cables, then have at it. Enjoy the SQ benefits!

Very interesting experiment you have going on here Doug. Read through most but not all of this thread as well as the original article posted on Dagogo. Bob Smith's response also made much sense although to have a complete understanding of all he had to say would require another reading or two at least for me.

I'm sure some EE on this website will correct me if I'm wrong but wouldn't it be easier, much easier in fact to create your own interconnects using two twisted pairs of high quality wire using a cross connected method. By that I mean each pair would have a positive and negative and both positives and both negatives are soldered to respective terminals on the RCA plugs. Shielding if needed could be added as well. To my way of thinking this is a far simpler way of accomplishing what you're doing with a litany of accessories. The exact same method could also be used on XLR plugs as well but with the addition of a third wire be it shielding or otherwise. 

It is worth noting some cable companies prefer to use twisted pair wire vs coaxial for line level interconnects. Ray Kimber I believe is a big proponent of this implementation. 

In the past I have built cables like this myself, both RCA and XLR using nothing more than dissected CAT 5 cabling. Granted probably not the best copper available but it made for an inexpensive easy to assemble test and experiment. 

Now all that out of the way, what I don't understand and surely someone will school me on this is why you think doubling the capacitance on an already low capacitance set of interconnects will create harmful oscillation between pre-amp and amp. I know this is true for wide bandwidth amplifiers where high capacitance speaker cable is used to drive the speakers. Goertz flat wire as well as excessive multiple braided wires come to mind, but only on amps that have high bandwidth. There are numerous cable companies manufacturing interconnects both RCA and XLR with much higher capacitance than we are discussing using any of these experiments and to the best of my knowledge without any harm. I do understand your sense of caution but not entirely sure what translates to the amp/speaker combination also translates to pre-amp to amp or line source to pre-amp. Hopefully this make sense.