The Mackie MR5s are a pair of active monitors designed for use in the recording studio.  I've used these monitors for both monitoring during recording and for a little bit of mixing, but not enough to get a great feel for them in terms of mixing.  They are active monitors so they don't require an external power supply or anything and simply run by themselves.  They each have an XLR connection and have some minimal EQ for different room situations.

SOUNDS

The sound quality heard from the Mackie MR5s is pretty great considering the price, but will only take you so far.  They are perfect for the home or project studio owner looking for a real cheap pair of studio monitors that will give you a pretty accurate read on your sound.  They aren't the best for mixing as they don't cover the low end all that well, but for the price you really can't expect that.  They do work great for monitoring during recording or simple playback and also will work well for A-Bing mixes.  However, I wouldn't recommend them to someone who will be mixing a lot as they aren't adequate for that.


OVERALL OPINION

I've only used the Mackie MR5s a handful of times, but I've used them enough to know what they sound like and have a good idea of what they can do.  While they do have a good sound quality, of course they don't match the high end studio monitors and for this price I don't think that anyone would expect them to.  The price is really the best part about the MR5s as this makes them accessible to people with just about any price range.  If you are looking for a dirt cheap set of studio monitors these are definitely worth a look, but if you want something to mix on and that will give you a truly accurate sound, check out the Mackie HR824s as that is about the cheapest you'll get for a good set of studio monitors.