I'm in the market for a new set of computer speakers, so I was excited when I happened on this review from Cnet's Audiophiliac, singing the praises of Alesis M1 Active 520 Powered Studio Monitor, a $177 pair of budget-speakers that are intended as pro monitors. They takeXLR and TRS plugs (the reviewer, Steve Guttenberg, recommends this $6 cable to convert to 1/4" output). According to Steve Guttenberg, "The bass is solid, the midrange is clear, and the treble detailed."
The M1 Active520 is a professional monitor speaker, so it doesn't have an RCA input, just XLR and TRS 1/4-inch input jacks on the rear panel. Chances are your computer or digital converter doesn't have those jacks, but the work around solution is simple enough, just buy a $6 RCA-to-1/4-inch plug cable to hook up the M1 Active520 to your desktop system. The speaker measures 6.5 inches wide by 10.5 inches high by 7.75 inches deep, and it weighs 13 pounds. There's a rear-mounted bass port, so you'll need to place the speakers at least six inches away from the wall for best sound.
The bass is solid, the midrange is clear, and the treble detailed. Designed as a pro monitor the M1 Active520 has a neutral, uncolored sound signature, so it doesn't add warmth or bump up any frequency range. You can alter the sound with the speaker's high, midrange, and low frequency equalization switches on the rear panel to accommodate your tonal balance preferences.
Candidate for best budget, pro quality desktop speaker: Alesis M1 Active520 [Steve Guttenberg/Cnet]