Cables do make a difference, it is well-documented. I definitely experienced it with AS10 and A10 in particular (low impedance, all BAs), largely when changing from thin stock cables.
What makes the difference is the impedance (actually the resistance part of it, since the capacitance and inductance are not a factor here). 1/16 rule works well, OK 1/24, if I pretend to be a discerning audiophile (that is the value of the single wire resistance to be less than 1/16 or 1/24 of the IEM impedance to stop matter - silver or copper or whatever conducts).
I do have three pure silver cables. I wish they could sound different, but they are not, when the resistance is the same to copper or spc. The problem of direct comparisons - the need to be sure that the diameters of the wires are the same, otherwise you compare thickness more than material.
4-core litz are thinner, so I can believe to some difference with the 16 cores.
Now, some "pure copper" cables (if not most) are still silver plated for the oxidation protection and then just have the copper-coloured insulation.
So those who hear the difference between pure copper and spc just make me chuckle...
Speaking of KBear to be at least somewhat on topic, they are my favourite 16-core cables - a bit of extra efforts make a nice difference.