I have the
Monster Home Theatre Reference PowerCenter™ HTS 2600 with Clean Power™ Stage 2 v.2.0. It's their second from bottom model.
I really like it, and am very glad I have it. But, If you're getting this because you think it will have an effect on the way your system sounds, I would save the money. If, on the other hand, you are interested in getting some protection for your equipment, that has some nice features, then by all means jump on one.
One of the things I like about it is that it has a couple of outlets which are timed. If you plug your sub and your amplifier (if you have one) into those outlets, everything else comes on first thus preventing any "thump" from the speakers which can occur if the amps come on first, or even at the same time.
There's another thing I like about it which is going to be tricky to explain. My 2600 is not remote controlled, which means that I have to get up and go turn it on manually. However, there is a way around this. You plug the powercenter into the wall, then plug your receiver or preamp into an unswitched outlet in the powercenter. Anything you plug into the powercenter's unswitched outlets will operate without the powercenter being on. Then, strangely, there is a second power cord on the powercenter which you plug into a switched AC outlet on your receiver or preamp. Now, when you turn on your receiver, which of course can be done with your remote, the powercenter comes on and turns on any of your equipment you have plugged into the powercenter's switched, and timed outlets.
I feel Monster products are, in general, overpriced, so I got my unit on Ebay for considerably less than list price. I did so with some trepidation, but the whole transaction went smoothly.