I'm thinking about upgrading my computer speakers. Right now I am using a Logitech 2.1 system that includes very large subwoofer / amplifier cube. These speakers are listenable and non-fatiguing. I'm looking for an upgrade to a better system with built-in amplification, hopefully without a huge subwoofer box. What are the best choices for self-powered monitors that are superior to the Bose / Logitech / Klipsch offerings?