Does power conditioning really matter?

My experience is that the Monsters, especially for the money, do just fine! They make a quieter background, for better contrast of sound, and a quieter picture in my experience. In fact, I've had lots of different "higher end" conditioners and power-stations in my system, and it's usually system/area dependent, at best! Basically, results vary with this stuff. I've yet to EVER read one review on any conditioner, variac, power supply, whatever, that says "this product is the end-all-be-all, and does EVERYTHING perfect!...er, basically, "greatest line conditioner ever created!", basically. They all do something different. They all seam to offer pluses and minuses (show me ONE REVIEW, where some super well regarded and respected, long time audiophile review expert, has found the Valhala of conditioners! Yeah, the product doesn't exist basically.)
All that to say, not only have I used and do use/recommend the monster conditioners, but my experience is they do add benefits (if for nothing else, a big warranty coverage for your stuff if it gets fried), and better than most for the money overall, for little investment. And still, the ONLY way to find out of something works, is to try some and compare! But, if you don't have the time, I think you'll find the Monster, dollar per dollar, to offer good results, yes. (sold em in 5 audio stores over the years, plus custom, plus my systems).
Actually, I like the cheapo's for basic receiver systems (HTS1000/1100, whatever).

I use a very basic Monster strip (about $200 retail a few years back) in my system. It made a noticeable difference when added, greater clarity and focus I would say. I've felt no urge to try anything else. It works just fine at least in my case.

Try a Synergistic PowerCell 10 SE.
End of story.

I too use a very inexpensive Monster strip, which is an excellent surge protector and my gear sounds better with it than with the power conditioner I have tried.

I started with a MOnster AVS 2000 which I got for a "song" (since they are ridiculously overpriced) and it was adequate untilmy system got better. Though frequent experimentation and demos, I ended up with a BPT 3.5 Signature Plus about 4 years ago. Huge improvement over the Monster in every area - my system really "opened up" tremendously. I hadn't realized how much information and dynamics I was missing until I made the change.

I have also worked my way through lots of cabling over the years as my system has improved with interesting results. I began to realize, at least in my system, that the more resolving my system became, the more of a difference cabling made. I liken this to the prior example of video differences being more easily discernible on an 8' projection TV than a 30" TV. There certainly is no right or wrong here - its all about your particular perception. System synergy is also very important - a conditioner that sounds great in 1 system might not work for another at all.

Personally, I now have all SR Tesla cabling, and will be trying their new Powercell 10-SE next week. Notice I said trying, not necessarily buying. IMO it is critical to try something in your system before committing to purchase, for all the reasons stated - you might not even hear a difference and have just purchased a boat anchor!!

So, IMO, power conditioning definitely "matters". Each person's decision as to what works best for them can only be discovered by demoing in your own system. I think these forums are very helpful to get some jumping-off points for the audition process.