alexatpos, thanks for providing the info on the specs. Those look like very fine components with class A tube power; I'm guessing very sweet sound.
One thought that strikes me is what appears to be three outputs, 4,8, 16 Ohm. Are you by chance using the 16 Ohm output with the Schroeder Method cables? I'm wondering if that would introduce the effect you are hearing. Is your system appropriate to try the 4 and 8 Ohm outputs, i.e. speakers appropriate? It would be interesting to see if the output influences the result of the Schroeder Method. Please confer if needed prior to attempting. But, it sounds like you know what you are doing.
Stringreen, by saying phono sounds WAY better than CD, are you suggesting that the CD got worse, or only that the phono is enhanced more greatly? It is hard to understand your comment the way it is worded. I'm asking because alexatpos is using a CD player and is not getting a good result currently. It may be correctable.