First: Sound deadener or Fiberglass?

I was curious wich do you prefer first? I will be making kick panels for my car in the next couple of weeks and also making a fiberglass amp container in my trunk(Not in the spare tire well but there is a small compartment connected to it that fits both of my amps and want to put them in there and run fans to keep them cool) I've never done either before, so I wasn't sure which I should do first. I was thinking of "dynamatting" first but I want to do the trunk and the car doors atleast, so I wasn't sure if I should "dynamat" before or after the fiberglass. I doubt I will be "dynamatting" my whole floor where the seats are. Thanks inadvance!

:Cliffnotes: Want to dynamat my trunk and doors but want to make a fiberglass compartment for my amps near the spare tire well and not sure which to do first because I dont' want one to cause installation problems to the other.

not a problem