My sub is wired with a phono, I went out to Maplins and bought a sheilded pair, try that mate.

It sounds like you do need a better shielded sub cable.

If I understand your problem correctly, your speaker cable to your sub is picking up a radio station signal and somehow allows the signal to travel backwards through the sub amp and then be routed through only the two rear channel amplifiers to the rear speakers. Oh yea there is also the question of how the RF signal gets converted from RF to audio frequency. Is this an AM or FM conversion? I know that this stuff does happen, but it takes so many things to be in alignment to work, that the odds are so much against it happening. So Cool.

I had an extremely baffling ground loop hum in my subwoofer connection years ago. It actually traced back to my cable tv connection which was on the same wall. It took me several frustrating months of complaints to get Charter Cable to send an actual technician (not an installer) to check it out. The installers were all telling me it was my equipment, but I knew better. The tech found that the run to the power line was too long, causing the hum. They ran it on a shorter path to a ground rod under the power meter, then to the wall. Solved the problem.

This may not be relevant to your situation, but the tech told me it is almost never the equipment, but usually some bad ground source/connection that causes the problem.

Good luck!

Where were you on February 25, 2007 ?