Musical Fidelity A1000 power supply problem

Hi,
I have a power problem with my Musical Fidelity A 1000 amplifier. I'm eager for someone to give me an idea what might be the problem.  The amplifier keeps blowing the two 6.3amp fuses intermittently while running. It may occur after a few hours or even when running for less than an hour. I tested the separate power supply on its own for twelve hours and no fuses blew. I connected one of the power feeder cables into the amplifier and both front led's  remained on for  about another twelve hours. Normally both fuses blow when both power supply cables are connected  to the amplifier itself.
Any ideas will be kindly appreciated.