Subwoofers.....Leave On/Off?

I run dual Sunfire Sub Juniors in one of my A/V system and really like what they bring to the game.
They are connected to independent power strips, which I use to turn them on/off since they lack the
auto on/off feature most subs now have. Both subs emit a sizable thump when I power them up/down,
making me wonder if I'm doing more harm than good by not leaving them on full-time.

My monthly power bill reflects the amount of equipment I have plugged in throughout my home, so I'm
trying to lighten the load, so to speak.