Mixing and Mastering Tip #004
Always check your mixdowns and masters in mono, I usually check before I mix/master and after I mix/master as well as after doing any drastic change throughout the process (especially if it involves heavy eq or stereo/panning.
I will give you a few reasons you want to do this, everyone wants a wide and interesting mixdown, but most of the people hearing your song are going to hear it in mono. Also when you play it in the club it'll be playing in mono usually. This may seem like something tweaky and tedious but it happens more than you think. I've had open hi hats that sounded way off in mono, and also panned/delayed pads (for stereo effect) that sounded weird in mono. I only discovered how truly important this was in the past 12 months or so but in those previous instances I wished i had checked it during sound design.