To answer your actual question, here's a Siemen source for Cat 5 vs Cat 5e:
http://www.siemon.com/white_papers/9...mystifying.asp
Another important issue: Did they use Plenum (PLN) cable or PVC? I'd definitely verify this since it's inwall. The issue is fire safety.
It has been pointed out that with Monster Cable, you're paying for their advertising. However, there may be more to the story than that. If you've ever actually visited MC (I have) there are trucks getting loaded almost as far as the eye can see. OK, I'm exaggerating a little, but it's...
Assume there is a difference between cheap and expensive interconnects and cables. Would there be a nontrivial difference between high-end cables designed for video and high-end cables designed for audio?
Would you change your mind and admit there's SOME possibility if a harmonic was being generated? Soldiers break rank on a bridge to avoid the off-chance of creating a harmonic and having the bridge go boom.
There's no way to know for sure, though it's highly unlikely that HT is the cause. For the simple reason that if it were this would happen a lot more often. The best thing to do is blast away. If it happens AGAIN, and assuming the specialist retightened properly, then you have your answer.
No point in jumping to conclusions. Obviously, you'll have to repair the damage. When you do so, be sure to find out EXACTLY what the problem is. If you have a line that burst, then your subs are not to blame. If you have a fitting that worked loose, then maybe the subs were contributory...
In a nearby thread, "Phantom Center", there's some discussion on the importance of a real center. Just for fun (or for allocating $$$), let's rank speaker importance. Put another way, if they all cost the same, which speaker would you least like to blow just before a DVD evening? Anyone (or...