Hate to see problems like this with Axioms, but there are other factors too. There is a guy down the street from me that has Rockets and his sub died on him, he got a replacement, and a few weeks later, that one was dead. He was using some expensive surge protection gear (not saying it is great, just expensive). In the end it was his $1200 (purchased less than a year ago) Denon receiver (don't recall the model, but could find out)... It seemed that the receiver was never letting the sub shut off, but was, instead, sending it a signal that was too low for the sub to produce, but at high volumes, or something strange like that, so he never heard it, but the amp was processing the signal non-stop, overheated and died. That was the best explaination he got from the folks at Rocket (AV123 or whatever) and Denon. Denon replaced his receiver, and sent him a gift card for $100 to Amazon.com for his troubles. He is now on his 3rd sub, and is having no problems in over 2 months.
I also have a SVS 20-39PCi sub that the amp went wacko on me after a couple of months. I tried different outlets, different cables, different sources (2 different receivers) and it still would do this super loud, low frequency rumble for no reason and at odd times. Got a new amp, and it seems to have fixed the problem.
They all have their flaws, and not everything is made 100% perfect. After all, humans are involved in the manufacturing process, but I can tell you this, it may not be the amps fault. Then again, you may be hitting some odd thing that only impacts your exact set up, and any significant change (such as a totally different piece of equipment like a different brand.model sub) may break that particular set of variables.
It is frustrating, I know, trying to troubleshoot, and getting nowhere sometimes, but I just want to make sure that you realize that you may get a different brand sub and have the same problem, or not...
Good luck. I am glad that I am no longer in the position that you are. You'll make it through...
