I have a set of these, and I totally agree with Bryan on this. Anything above 10 - 11 o'clock is too much bass. I think the best is probably within the 8 - 10 o'clock depending on the audio source you're listening to. The sound quality is still really good, although the midrange is being produced by the bass. If you turn up the bass too much it will get overpowered and the sound becomes really muddy.
I tested it without a sound card, connected to a PC, and then directly to a media player. It will definitely be enough for a small room, and especially enough if you're going to use it for general home theatre use. Turning the dial over 12 o'clock max would definitely be a big NO. While watching movies and music, I couldn't hear any distortion at max volumes; if there is, it's really minimal.
For the price, I think it's actually a good purchase for those who want to replace existing 2.1 systems or upgrade from an inexpensive 2.0 speaker set.