I maybe onto something here. I *think* that the sub is defective and B&W is looking into resolving my problem. I may have to send it to Singapore for repair - the driver it self is great.
The problem lies with the circuitry that drives teh voice coils. The only thing that I haven't tested is the 'power cord' per say. I'm not using the power cord supplied with the sub, but instead a regular PC IDC jack power cord. Yes, it has a 10A fuse but it would have blown if I had driven the sub excessively and it hasn't. This unit should be allowed at least 13A, and I think the original cable from B&W has a 14A fuse (need to check this)..but this is only if one plans to really drive it hard, and this isn't my case...at least for now
I have tested everything, tried a different coax, tons of different settings on the receiver (it isn't the receiver) and even done a 'thermal' test to isolate thermal shutdown. Right now the sub and receiver share the 1KVA UPS while all the other stuff have been shifted onto a 600VA UPS, so this should allow for more headroom.
I'm getting operational times of 1hr 25mins to 1hr 40mins (max) and I hope that B&W can help sort this out.
--Mike