don't know if this i helpful or not,
but i had the smae problem with a Yamaha amp. It 'boomed' whenever a setting or function or anything was changed in the unit.
The fault lay in with the yamaha unit (it was literally faulty) and i just had it replaced, as that is not meant to happen.
But FIRST contact Pioneer as there may be a setting you just need to disable, otherwise, if it's a new unit, i'd just return it and say you just want a unit that gives sound effects only when needed.