Hi,
 
I use a set of Klipsch THX.  Its a satelite with sub system.  Has excellent volume and is a killer speaker for pc or most anything else you put on it.  The hook up is a standard 1/8 jack pc plug that I brought a 1/8 to rca adapter for. From their the standard rca to 1/4 cable to my interface works really well.  So any decent pc setup (wont take up a lot of space either) could work for you. HTH..

I saw a guy who was using some plain old powered monitors like we use in the studio on his computer. 

It sounded pretty good and someone gave him the speakers, so...... 

I often use the studio monitors to listen to music..... sounds good. 

Guitarhacker : "I often use the studio monitors to listen to music..... sounds good."

I'd much rather spend, say, 1000$ on a good set of monitors and listen to everything on those
than have a set of monitors and a set of hi-fi speakers (which still need an amp) at 500$ each.

I had a pair of these that lasted a lifetime and they were great sounding speakers for the job we do
http://www.daleproaudio.com/p-8356-m-audio-studiophile-av-30-3-15-watt-compact-monitor-speakers-pair.aspx?gclid=CPGxwcHZpLYCFcqd4AodhysAsg

not a big m audio fan but there speakers don't have drivers so I can live with that.
(hence the joke about m audios drivers taking years to be updated)

 You have 2 option ..Power amp and speakers or power'd speakers. JBL Control 1 Pro Compact Speaker - Pair 165.00 http://www.musiciansfriend.com/genelec $$$$