So I already have a pair of Dunu DN-1000 but they don't work well in the gym. They keep falling out my ears and such, and I'm afraid sweat will ruin it. I've tried all the buds but when I'm working out it keeps falling out. So I'm looking for a pair of headphones that are light and preferably sweat proof. I don't care if they are over ears or in ears, as long as they stay on when I work out. All the headphones I tried have too much bass, I need a more balanced sound. I have a budget of $100 CAD.

Sennheiser PMX 680
 
They sound great and will not fall out of your ears. The Sennheiser CX 680 are also great if you want more isolation, but they are a tad uncomfortable.