I have a pair of these working for the past year, but one has just started making a crackling sound. Unit still passes audio, EQ functions well, everything seems as normal but theres a crackling. Occasionally there will be a rather large peak, which looking at the waveform, they come in twos, one positive, one negative then just crackling for a minute then another pair of large peaks.
Ive taken the board apart, crackling is still present without the freq selection board, still present without op amps, I've reflowed most of the joints, still crackling no matter what. Any ideas?