Very few "rules" in audio, but I've always believed small rooms require small speakers. Big floor-standers with large woofers and deep bass require larger rooms for the bass to sound right.
Luckily, I've found many small bookshelf speakers sound great--I use a pair of Tang-Band full-range drivers, but had good results with dozens of cheaper brands. Apparently, it is much harder to design a good full-range speaker than a mini-monitor.
I've found speaker and room interaction to be extremely important, much more so than any other component, brand name or accessory.
Luckily, I've found many small bookshelf speakers sound great--I use a pair of Tang-Band full-range drivers, but had good results with dozens of cheaper brands. Apparently, it is much harder to design a good full-range speaker than a mini-monitor.
I've found speaker and room interaction to be extremely important, much more so than any other component, brand name or accessory.