jackdimebag

I have a pod hd pro x and a Rocktron Velocity 300. I was told I need to run my poweramp in bridged mono but when I do that I get lots of pops and buzzing noise. I'm not sure i'm doing something wrong or if the poweramp is broke? My pod global settings are all correct with the stacked power amp setting etc. Any help would be appriciated as its getting rather annoying. *Works perfect when its in stereo and only one speaker cable going to my cab. Thanks