I am not sure that this is widely discussed and I am posting it on here not for technical help, but to let you know what a difference Multi Band is when mixing a track and how it effects the overall dynamics of the sound. It tightens up your music giving it more time and space. Just wondered how many of you use this technique. I first noticed something similar when watching into the lair where Pensado used a technique on Bass. I figured that you can use it on many other things to cut or exaggerate frequencies.
 
http://youtu.be/qmTYjQLz5Zc
 
check it out

multiband compression,
is the single easiest way to quickly ruin your mix.
 
just sayin'

It can be a powerful tool and it also can be used on individual tracks too.  On a mix it can also be OK but you have to be careful with wide range program material though.
 
The trick is to set all the thresholds of the various bands so you get a very similar amount of gain reduction in all of them. Then the overall tone or EQ of your mix won't change much.  Most mastering engineers I know prefer single band compression over a whole mix, not multiband.
 
On an individual track it can be harder to setup because of the nature of the signal it is working on.  It won't be as wide band as a mix.  But yes it can be helpful if there is just an area of the spectrum that is a bit over the top while the rest is normal.  It can tame that area quite well.
 
When your source tracks are of higher quality then you need it less if at all.