Why does this Biwire set-up not work?

Anything's possible, but I'm guessing it won't make any difference.

And if you do not notice a difference, simply sell one set.

-IMO

It's strange, on my Krell monos today I moved the right channel speaker wires from the bottom to the top posts to get them out of the way of the power cord. The soundstage and focus was completly lost.

What do you mean by "not right?"

how much time have you given the cable to break in ?

expect 200-300 hours

The issues is related with the internal rewiring from the binding post at the speakers to how it links inside the crossover board of the speakers you are using. While having the jumpers removed and thinking that a set of cables from the amp goes to the color associated with it, the problem may be that the second pair,while innocently doing the same thing to matching the color to the posts...a phasing problem occurs with the speakers, why? Some crossovers have their hi frequencies inverted by the design it was meant to be. The inversion is in the wiring that you don't get to see and not associate unless you look at the board.

I answered eairler in this thread that when I moved my right channel speaker cables to the second set of amp output terminals the sound got out of focus with no soundstage. After a second look at what I had done I noticed that the top set of terminals have the positive (red) on top and the bottom set has the positive on the bottom terminal, that is where I made my mistake. Is it possible you hooked one set of wires out of phase?