filter capacitors: The filter capacitors are among the most conspicuous components inside an amplifier. They usually occur there in larger numbers and look like a collection of "batteries". In a way, they also work that way – filter capacitors serve as energy suppliers on the one hand.
On the other hand, filter capacitors are used to clean the incoming DC voltage (the AC voltage from the socket is rectified immediately after its transformation) from any residual ripples. The total capacitance of the filter capacitors of a HiFiamplifier is often between 30.000 and 500.000 microfarads - but the latter is a very high value.