I have a new Aguilar 924 outboard pre-amp. I noticed the volume with the bass plugged in is noticably lower than the volume of the bass plugged directly into the amp when the knob is pointed at 12:00. The only way to exceed the normal volume of the bass is to turn the volume knob to the next to the last position. Is this normal or is there a problem I need to investigate? I've used 2 sets of batteries and results are the same.