For the price difference its a no brainer to go for the monoprice cable. However there are some quality differences favouring the Blue Jeans that I see. The Canare connectors on the Blue Jeans are much better build quality that those RCA's. Shielding looks the same. Capacitance is lower on the Blue Jeans which theoretically is what you want in an interconnect. Still not worth the price difference.
I doubt you can hear the difference in cable capacitance in sub bass over that distance. The bigger concern is how noisy is your environment and at 40ft thats in the zone where I would start to think about balanced cables to make sure there is no extraneous noise.
Sonic differences do exist in cables, but are so dependent on shielding, capacitance, inductance, impedance, noise in the environment and especially how the cable interacts with your player,amp or speaker/subs that generalizations are near impossible.
