A few things you should check out first... Is the hum present when none of the pedals are hooked up, i.e. just guitar straight into amp? If so, it could just be the power outlet that you're plugged into. Try plugging into a different outlet, and/or make sure you and your amp aren't close to a TV, stereo, computer, etc... as these can cause some nasty humming. If none of that is the case, start by connecting one pedal at a time until the hum appears. If the hum appears after connecting a certain pedal, disconnect it and connect the rest of the pedals. if the hum is still there, you might just need better cables. Hosa is a really cheap brand of cables, and the quality of the cable really does make a difference.