For the 100hz dip, I recommend moving your speakers/desk at least 1 foot in any direction and testing again.
Then moving even further away than that and testing again.
Finally, I would test with the speakers dead center of your room.
Now you have 3 measurements, original, 1 foot away, 3 feet away and dead center of the room.
Why?
You need to determine if it is a room generated null that you are fighting. Because I am sure you are asking if it is the amp, the speakers, the direction they are aimed, etc.
Once you can confirm that it is a room generated null or not you can proceed on to the next concern. That means that if it is a null, you can (generally) only fix it by moving the speakers.
Then moving even further away than that and testing again.
Finally, I would test with the speakers dead center of your room.
Now you have 3 measurements, original, 1 foot away, 3 feet away and dead center of the room.
Why?
You need to determine if it is a room generated null that you are fighting. Because I am sure you are asking if it is the amp, the speakers, the direction they are aimed, etc.
Once you can confirm that it is a room generated null or not you can proceed on to the next concern. That means that if it is a null, you can (generally) only fix it by moving the speakers.
