Power Conditioning is the removal of EMF or RFI interference on the power line. This can be seen as 'garbage' on the sine wave.
Check out
this graphic to see what I mean.
The best 'real world' example of power line noise and how it affects your system would be to plug in your vacuum cleaner and turn it on while you're watching TV. your picture may become snowy or blurry (if watching cable) and you can hear audio issues (popping, static).
Devices with motors are NOTORIOUS for making noise on power lines.
The way Monster (and other products work) is they have the incoming wall AC go through an Isolation Transformer to give the electrical coming into the unit a clean sine wave clear of noise.
Then, each (set, usually) of outlets has their own Isolation Filter, so you wont get noise on the power inside the unit. An Isolation Filter is basically a very scaled down version of an Isolation Transformer.
Monster is running a $50 MIR on the Monster HTS 3500 MKII, which can be had from OneCall for $399 (
Link) before rebate, bringing total cost to $349. This is the power center I use and I am very pleased with its performance.
I can say with certainty that there is a difference in Monster's "Stage" ratings. I bought a coax cable amplifier because my apartment receives a weak cable signal, so some digital channels were cutting out. I plugged this amplifier into a Monster HTS200 Stage 1 Power filter (which actually goes over an outlet, it's their smallest offering), thinking it would provide enough protection.
Soon after installing this setup, my wife placed a fan in our living room and turned it on. When she did this, I saw the video signal distort briefly. How could this be?! I have my system plugged into a HTS3500 Stage 3 filter! Oh wait, the cable AMP is on an in-wall stage 1. After running longer coax and plugging the amp into my Stage 3 center, the issue went away.
Every situation is different though. I'd suggest purchasing a moderately priced (and reliable) power filter and giving it a go. If you don't notice a difference, then return it for a cheaper model.
