Re:Are power conditioner/surge protectors really necessary?

"will I actually notice a difference in the picture or audio quality when using a power conditioner?"

With tongue in cheek I'll answer that you will, only after a lightning strike on a nearby power pole. These items are only additional line and surge protection. I install one per device in the house and the plan here is that with all the surge protectors installed the total number of joules that can be absorbed due to an out of bounds electrical spike might do no damage.

Bob