My SVS PS1-ISD is an incredible sub. Everything you can reasponably ask a sub to do is there in spades: depth, punch, speed, wow-factor, musicality, knick-knack-knocking, etc.

If you care about this sort of thing, SVS subs are designed and built in the US (Ohio, to be precise). The drivers are built according to SVS spec by TC Sounds in San Diego.
I can explain it to you but I can't understand it for you.