I've got a 4x10 Delta Avatar, which is rated for 1400 watts. I decided to see how loud I could get yesterday, so I turned my 450 watt head all the way up. (Before you tell me that my 450 watt head is only putting 180 watts into the cab because it's 8 ohm... no, the cab is 2 ohms. The head is rated for it as well.) My EQ settings are usually a slightly boosted treble, a moderatley boosted high mids, and a bass boosted about the same as the high mids. So, instead of turning the master and the gain all the way up at once... I decided to do it in increments for safety. I started by turning the gain all the way up and the master about half way. I hit an open E and could literally see my speakers jump in response. After watching them vibrate (basically looked like a blur of some sort) for a moment I started to get feedback and muted the bass. I tried it again with a few different notes and got the same results. This amount of power kind of worried me... so I stopped and turned down. It was too loud to really tell if it was distorting or not. I also have no idea what kind of hell this was putting my tweeter through. So I mean, 450 watts into a 1400 rated cab... is there really anything to worry about or am I just being a wuss?