I have a Monster HTS 5000 that incorporates several filters. I purchased this on Ebay and paid about $300 for it new (refurbished). The first one came in and emitted a noise when the blue light was set to on, I returned it for another one. I mention this only based on the basis that it was a dealer selling these.
In addition to voltage regulation on this version, there is a fair amount of filtering. Understand that this is not a regenerating power supply, but a passive design. Buying one of these smart (ie. on Ebay) for a fraction of the "new" price will allow you to determine its impact on your system and whether the improvement is enough to satisfy your needs or if you need to go beyond.
When I installed mine, the picture quality on my plasma improved immediately. I also recognized an immediate improvement in my sound quality. Since lightbulbs don't last in my house more than 30 days, I am sure my power is not very clean/good. So my experience may be more pronounced than yours, assuming you have cleaner power.
At about $300 for one of the HTS versions, I really don't see how you can go wrong. I would like to get a regenerating design, but not yet ready to cough up the $1,500 for this. Keeping my eye out for a used one at a great price. My recommendation is to start with the Monster or similar device that offers both voltage control and filtering. If you want a PDF copy of my manual, just let me know and I can e-mail it. Is monster the best? I am sure it is no where near the best. But the units were designed by Marsh, think about what other brands he did the design work that made them famous!!!!
