Unamplified speakers: The PSB Alpha B1 loudspeakers seem to be highly rated and in my price range ($279) as are the Paradigm Atom Monitor v.5's ($249). Onix x-ls speakers have a good review or two and more favorable pricing ($200)
When looking for loud speakers for computer systems, it seems that you can find only amplified systems. Of these, the M-Audio Studiophile DX4 seems to be rated highly for audio source materials (not games) and comes in at an affordable price point. Samson Resolv 40a's are similar (repurposed monitors) but have higher power ratings.
Music to look into: Miles Davis and Gil Evans' Porgy and Bess