I seem to be intermitently losing the left channel on my Dav 500, it seems mostly to happen when it's first switched on, often unpluging from the mains resets it to normal. This happens in all modes including line inputs,radio,CD etc. , when it happens I've run the test tone and the left speaker is dead. I've checked that the speaker cable is connected properly so far as I can see. BTW the fault is also present when connected to headphones which I think tends to rule out a speaker problem. Does anyone have any ideas what might be wrong?