I can't resist saying something...
In my experience, it's a bit off-the-mark to specifically worry about whether speakers are "studio monitors" or not. Maybe some of you remember my slightly embarassing post about looking for studio monitors, and suddenly becoming fixated on the idea of finding a set of Polk Audio Monitor 5s, vintage circa 1978. Well, I found them. And it's the best $75.00 I've ever spent (admittedly, you'll normally find them for US $250-ish). Now, before everybody points out what a fool I must be, let me say that (to be totally cliche) my main deduction after using these things for a couple of months is -- "they just don't make them like they used to!"
When I started looking for monitors, like everybody, I went to my local music shop and listened to a wide variety, from within my price-range, to well beyond it (no, my original range wasn't $75!). The ones I liked best, and which were vaguely within my range, were the Mackie's (I think it's HR824). I listened to Berhingers and Tapcos, Genelecs, and a very nice pair of Blue Skys (yes, they were wonderful, but too pricey for me). But the main thing I came away with from this experience was the feeling that "flat" is basically an illusion, laying somewhere between an analytic fallacy and a psychoacoustic Holy Grail. Basically, my subjective discrimination of "flat" changed, however slightly, with each new set I listened to. This left me thinking... "God, I guess I just need speakers that *sound* reasonably flat to me, and that I don't feel irritated listening to!"
So I went away, somewhat dismayed, and for no good reason started dreaming of this ancient set of Polks my parents had when I was a kid. It somehow became stuck in my head that *those* had the sound I was after (yes, this is probably getting somewhat Fruedian!). Then, lo and behold, I found some -- and in my home town, no less! Honestly, these things sound brilliant: remarkably clean, detailed soundstage, flat response, tight bass, plenty of power. I would, in all honesty, place them well above the Berhingers and not far off the Mackies (no, I'm not stupid, they are *not* Genelecs or Blue Skys!).
So, to cut an already long story short(er), it seems to me the most vital points, in order of importance, are:
1) Knowing your speakers
2) Having speakers you can listen to for hours (fatigue will affect decisions)
3) Having a "flat" response
4) Playing your masters on as many different systems as possible
The old Polks did it for me. (But by no means am I suggesting they will "do it" for anyone else!). cheers!
J.
-- ps -- It is worth note that most hi-fi speakers of today are really quite "sculpted" in sound, and not particularly flat. I guess they sell better when they hide the rough edges... don't know... Also, note that "home theatre" speakers seem to be the big offenders in this aspect (gotta make them 'splosions real scaaary!). And admittedly, Polk has become one of the worst for "juicing up" the sound... too bad.