Cables
Try to keep them as short as possible. By its electrical
parameters, a long conductor will have a bigger influence on the
sound than a short one. It may also work as an antenna and thus
receive various signals, that may become a constant noise in an
active subwoofer.
Make sure that all connections are clean and not oxidated. All
connections should be mechanically stable, both power, signal
and loudspeaker cables. Signal cables should be separated from
other cables.
Finally:
Please remember that good sound is a matter of taste, so you
have to experiment to obtain it. We wish you the best luck!