Maybe cables matter, but y’all understand that bi-wiring does absolutely nothing, right? You’re still sending a full-range signal down both pairs, the crossovers still do their low-pass/high-pass roles. And at 10-12 ft the series resistance is still a small fraction of the series resistance of the low-pass inductor.
I try not to say anything too technical on the forums because every accountant and MBA claiming to be engineering PhDs from Purdue, MIT, etc (the all knowing seers!)) could get their enormous egos hurt these days. Some speaker peddlers who buy drivers from someone else, put em in a box and sell it to y’all for beacoup bucks don’t know diddly either and are also a part of the misinformation transmission group.
The following information is just to get you a bit more informed about this. So, don’t get offended. In layman terms, when you apply a voltage to a drive unit, the current flow is nonlinear. i.e. If you put a linear voltage into a linear resistance, the current flow will be linear. If you put a linear voltage into a nonlinear resistance (such as a driver implementation in a speaker), the current flow is nonlinear.
For any driver, the impedance is a combination of the current going in the forwards and backwards direction (i.e. when a coil’s moving), i.e., it is a non-linear current flow. When you have a tweeter and woofer coupled through a crossover to a common ground point, that point is not the speaker’s negative terminal. True ground is back at the amp (not at the speaker) due to the wire going to the amp...so far so good?
As you may know, any speaker cable has a resistance associated with it, ---> non-linear current flow through the tweeter is generating a nonlinear voltage across that wire ---> the reference point for the voltage applied across the woofer has a nonlinear voltage applied to it by a small amount and vice versa ---> nonlinear contamination between the 2 drivers. (it is a small amount)...
The essence of biwiring is separating those wires and grounding them only at the amplifier such that the amplifier is a true ground point, and the nonlinear artifact/contamination (mentioned above) is removed.
Whether you hear it or not depends on the fidelity of your room, quality of your ear, any attention to detail that was paid to your speaker drivers, crossovers, amps, etc.
Just because you can’t hear it doesn’t mean no one else can hear it...
