toolbox 149, your post is greatly appreciated, because it's another sincere, unbiased assessment of the profound influence of Schroeder Method. You bring up a good point. Skeptics often default to an objection that seems logical, even though it's wrong. When I was first trying double ICs one of the first thoughts I had was, "Will the poor quality connection of a splitter or Y-cable destroy any advantage in doubling the wires?" I know how splitters and Y-cables influence the sound, as I have used them a lot. I typically will avoid them whenever possible. However, in judicious use they can vastly improve a system holistically.
I was hopeful that the doubling of the cables benefit would vastly outweigh the "drag" on the results due to splitters/Y-cables. I was right. The difference is profoundly superior to a single cable, despite the less than perfect connection. Obviously, this is not ideal. I have had some responses to Schroeder Method condemning it because I used splitters initially. This is not terribly astute. I was looking for proof of concept on the cheap rather than pay for double cables to be made. In addition, splitters and Y-cables allow for recombination of cables, a big bonus when putting it on trial. Overall, imo starting with the marginal cost of splitters or Y-cables as opposed to sourcing a double IC is a more sensible way to proceed if you demand proof of concept and are skeptical. I understand the notion that people don't want to pay money for something about which they are unsure. This is about as cheap as it comes to try an unorthodox method.
At this point I don't know what the limits might be for sets of double ICs, perhaps no limit. There is still much experimentation being done. Some have tried a triple IC, and I'm told it's marvelous. Lot's of fun for those who, having judged the "do at your own risk" nature of it, and have tried it! To date I know of no negative outcome. It's very good that people with alternative setups are also seeing the benefit immediately.