I've read (many times) here that when matching up a speaker cab and an amp head that you shouild use an amp that provides more power than what the cab is rated to handle so that you have lots of clean head room. Am I right so far? What does this mean? Does this mean that you'll blow your speakers before your amp starts clipping? When you have all that power - if you have twice as much power as your cab is rated for, how do you know when you've turned up too much? If my cab is rated for 200W noise / 400W program / 800W peak am I going to be underpowered with the 400W head I am getting?