Help choosing Power Conditioner

Completely new to this area. I would like a unit that:
a) regulates power, keeping it within the 120v range.
b) provides good and long-lasting surge protection
c) can be used with a power amp as well as preamp, and sources all together
d) Hopefully helps the audio, making it more open and dynamic without negative effects.

I need to say under about $750 used. My candidates are:
Monster HTPS7000
Monster AVS2000 (how are these two different)?
PS Audio Power Director 3.5
Blue Circle MR1200 Music Ring
Any others...
Thanks!