Switching to better RCA probably have more strands of copper per channel for ease of current flow, they may be shielded to prevent noise interference, maybe the tips are of a more conductive material, and finally maybe the exterior rubber is more durable.
How does this add up, well maybe your 2V Pre-amp reaches the amp at 2V and not 1.xx Volts (didn't bother to look up your HU Preamp)
What does this all do for the overall audio you hear, probably not enough to justify the cost.
However if the shortest route for your RCA run is next to you amp power wire and vehicle wiring, then maybe the added cost in quality is worth, not going through the hassle of routing you RCA's the long way and spending the money on the less quality for more length.
my 2 cents, !!