Sure, the title of this video reads like classic click-bait but in this case I actually stand by its claim! There are two knobs in Reason's mixer that far too often get overlooked by people new to mixing. Unsurprisingly, these knobs are seldom overlooked by professional mix engineers and once you learn to use them, you'll start using them just as much in everything you do.

The High Pass and Low Pass Filter in Reason's main mixer helps you achieve something called "frequency slotting," which is just jargon for this result: Your instruments won't be fighting each other for the same space in your mix. In this tutorial, Ryan shows us how to get clarity and definition out of your mix by mindfully considering the important frequencies for each instrument in your music.

Try out Reason here:
http://propellerheads.se/tryreason