Back in the 90`s I developed some asymetric 4-way using no absorbers what so ever, any kind of absorbers eats energy=reduces dynamics and kills ported output.
At the same time I discovered how to make absolutely inaudible audiocables, unlike any cable-manufacturer
As an old diy`er I`ve came upun some interesting alternatives. To those of you who has Access to the European marked; try to get tour hands on a piece of Vivanco KX-710 tv-coax and a pair of decent rca-plugs. This is the only digital coax I`ve ever heard outperform a optical AT&T