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!