I have owned a PowerPlant 300 for over a year now. When I bought it, I was a skeptic. I found it here at a good price, and figured I would try it, dislike it, and resell it. Here is is a year later, I am keeping it.
I run my CD Player and Pre on the PS-300, set to 90 Hz frequency, which seems to yield the best results. I do not have a fan or multiwave option, and I do not see the need for either. (The fan makes noise, I did not hear much difference on a PS300 that did have multiwave). My unit runs at about 110W output continously, and draws roughly 170 watts input, both meassured using a watt meter. So, your electric bill will be a touch higher. The unit gets, you guessed it, nice and warm. I have had more equipment plugged in, and just was not as happy with the results when the unit was running at 250W output; music seemed a bit less vibrant.
Another note, I run the unit at 90Hz output, which seems to yield best results with my CD player. However, there is a very slight audible buzz from the transformer in the CD player. (Very slight meaning: I put my ear on the CD player, I change the frequency from 60 to 90, and I hear the buzz become higher pitched and perceive it as being louder).
Overall, it made the quiet passages quiter, seemed to make the highs a little crisper, and the bass became a little tighter I think. They're small, but pleasing changes. I think I paid about $600 used for mine, and consider it well worth it.
Niels.