The amplifier has good performance, clean sound, and quiet operation (fan noise). Unfortunately, after some time a fault occurs where the volume of one channel — and gradually other channels as well — starts to fluctuate. It sounds as if someone were standing by the amplifier and suddenly turning channels down and up. After some more time, the channel stops playing completely (or is very heavily attenuated even at maximum gain). This fault starts to appear after approximately 1–1.5 years.
It’s true that we run the amplifier in a restaurant almost every day for about 14 hours a day, but throughout that time it plays at roughly 1/3 to 1/2 of its power (all four channels set to the same level). This fault has occurred with this model of amplifier in our case four times. Each time we filed a warranty claim, each time it was replaced with a new unit (thanks to Thomann for their great support), and we were told that some component on the board that controls the gain had failed — so I assume it’s the driver stage of the power amplifier.
Because this fault has occurred so many times, after roughly the same period of time, and always with the same symptoms, I assume it is a manufacturing defect or a design flaw of this amplifier model.
