I recently purchased a Cambridge Audio 640A V2 amplifier for my Mordaunt Short 914s. I do however have a nagging problem. When the speakers are wired to either output "A" or output "B", all is fine. The problem however occurs when I try to biwire and use both of the outputs together. When turning the amplifier on, the protection circuits engage, causing the protection LED to flash in single bursts (the manual says this is because of a DC tection). If I unplug one of the Low Frequency cables for either channel, it turns on fine. Also if I disable the B output (currently connected to the High Frequency inputs on the speaker) all is fine. Finally, if I turn the amplifier on with the B output disabled, then turn the B output back on whilst the amp is on, all works fine (currently what I have been doing). Any ideas as to what would cause this? Thanks, Andrew.