Electrical Hum

I'm not sure if this is the right area to post this, but here goes, I play Bass guitar, I have a new guitar and new bass amp, everything I play through developes a hum, In the Amp, through the Personal Aviom mini mixer, the sound tech says that it is either my guitar or my amp, when iI use the headphones on the Aviom there is a bad buzz that starts, when I play through the amp only and do not use a DI out box there is no hum, Question, can a ground look problem cause the buzz, I don't know how to find the problem or fix it, Thanks, Leaderman