I did a long extensive research on the matter about 1 year ago, my conclusion was that for me in my situation it was more priority to get grounded power.
Another consensus did seem to be that a lot of these cheaper products can do more harm then good, but in extreme situations where the power is very dirty and it really affects your gear they can be good. But a lot of the cheaper products on the market will actually make the sound quality worse, the filters can be destructive to transients. I would say a cheaper box might be more better in use on live gigs then in a private budget studio. If you have grounded power in your house it should be safe, and no need for a cheap furman box.
If you really want to make a good difference there seemed to be no shortcuts, the balanced Furman boxes was still on top of the list for most people, but as Julio mentioned they are very expensive, and might not be the first gear you "want" to buy, for a private studio. But the longer the studio grow and the more expensive gear you get you come to a point where the Balanced furman box might not be a big cost in percentage of the general gear.
Another point to consider when reading discussions on other forums about this object.. it is really hard to find a consensus the opinions are very very individual, every person seem to have a totally different view on the subject, and the discussions gets quickly in to really hardcore scientific discussion which only a real electrician can really understand fully. I have been recommended isolation transformers if you use non grounded power, to create it s own "grounded power" for the gear, but then there is also a lot of people who said it is useless bla bla bla
My reserach did anyway end up with not investing in any cheap furman box..
in a longer pespective it might be wise to invest in some of the balanced boxes by furman, but in current studio situation
it would not make sense, since it would be too big cost considering the total value of my studio gear.
