You need to have an experiment. Do you get the buzz with just the guitar plugged straight into the amp? If not, add the pedals one at a time and see where the problem starts.

Also, if you're playing anywhere near a CRT screen (PC monitor / TV etc) or with a mobile 'phone in your pocket - that won't help. Are your pedals mains or battery powered?

And for the finale - singlecoils are a little noisy. If you're playing a strat type guitar, try the 'in between' pickup selector positions (2& 4 out of 5).