I bought these to use a piano monitors for a compact space. The sound reproduction is quite good, and it is really quite nifty that they come with a hand-signed frequency response diagram for each speaker to show that the response for the specific speaker you bought is flat across the supported spectrum.
Sound quality: I played various types of music through these, and also used them as monitors for a Yamaha Electric Piano. The lowest end of the bass seems a bit weak, but I'm used to a 3 cubic foot subwoofer, so I'm probably biased. I had no complaints about the volume levels. These speakers do not give any impression of being underpowered for filling an office-sized room. I was slightly disappointed in the output when used with the piano (which was the primary reason for purchase). They sound good, but I believe the bottom end was lacking enough to make it sound less like a real piano that I'd like. Word of warning for those using these with a computer: the inputs are all "line in" impedance matched. Hooking them to a headphone jack noticeably degrades the quality. Turning the input trims all the way down seems to help.
Inputs: 1/4" and XLR. Neither of these are impedance matched for headphone jacks, which means that your computer needs to have a true "line out". They work great with my Mac Pro, but my two MacBook Pro's only have headphone out, and this ends up causing some noticeable distortion.
Adjustments: Each speaker has it's own amplifier (and power cord). The amplifier has some switch-based adjustments to help with the sound of the speakers in various placements (from free-standing to in a corner). The input trims are useful if you are coming from a source that isn't impedance matched, or has a variable amount of signal-to-noise based on output (e.g., our electric piano puts out a better signal at higher volumes, but then is too loud without this trim turned down).
Manufacturing/Build: The first thing you'll notice: these suckers are _heavy_. This is a good sign, in that a critical part of good sound in a speaker is the neutrality of the cabinet. A lightweight cabinet almost always means a reduction in sound quality. These are designed in Germany, but built in China. I was kinda hoping this wasn't the case, but it is. I was hoping any of the materials would pass European indoor air quality standards, but I seriously doubt it. They smell very strongly of glue when you first get them. I ran a 40Hz waveform at high volume through them for several weeks in order to help get the smell out. They are much better now, but the gasses they were putting off made my respiratory system feel a bit bad (my throat got really scratchy, etc), and I felt a bit dizzy from them at first. I would _not_ recommend these to people who have environmental injuries (as my partner does).
Overall, these are good powered speakers at a great price. If you don't have a true "line out" on whatever source you use to drive them, you might be disappointed.