The only disadvantage this set-up might pose compared to a more usual pair of speakers is the desk area required to place the amplifier. Specifically the unit takes up 250 x 52 x 170mm of your precious space, which isn't exactly excessive. A subwoofer would certainly take up more space, although most likely under, not on top of, a desk, of course.
Each speaker stands about a foot high and is finished in matt black plastic, such that they match the amp nicely. Four channels are each powered by their own 30W output, which translates - as I already hinted - to a tremendous amount of volume at your disposal. Even pushed to the extremes the clarity never drops and there's nary a hint of compression or distortion as you might find in a lesser set of speakers.
The lack of a subwoofer does mean the bass output is slightly lacking compared to a set of 2.1-channel speakers, but that's not to say there's none at all. In fact, the 'trumpet-like' design to the opening incorporated into the base of each speaker helps enhance those lower frequencies. However, if you're the kind of music listener that thinks that the more bass presence is felt, the better your audio sounds you'll want to look elsewhere. The Creative GigaWorks T3s or Razer Makos, for instance, deliver more on that front.
However, if clarity, precision and detail are important to you then the Concept B 200 USB speakers will be right up your street. The quality of their audio reproduction is nothing short of phenomenal. There's simply no other way to put it. I'm not exaggerating in the slightest to say that these are the best sounding PC speakers I've ever had the pleasure of listening to by a decent margin.