I've been having a hell of a time diagnosing a noise problem with my rig lately. Well, I finally solved part of it. I've been using Berkley & Jensen (BJ's house brand) 9V's for awhile and I'm not sure if it's just a bad batch, but they are noisy! I use them in a Church st9100 and NBox and when I shake the boxes (or just the batteries), I get significant static noise. Switched to Duracell - no noise.