Cambridge Audio A640 repair
My Cambridge Audio A640 integrated amplifier has been suffering from drop-outs and clicks for years. I discovered that it got better after switching sources a couple of times, which forces the output relays to open and close. This led me to believe that there could be a bad contact in the output relays.
I ordered a couple of new relays, put them in and the problem is fixed! Crystal clear sound again!
Update November 2020: it's still working perfectly, more than 5 years after the repair.