Originally Posted by
yggdrasil
Some amplifier design's has this turn-on thump.
A few years back I had a Norwegian amplifier with turn-on thump. The designer offered an upgrade, and when I called to make the appointment, I had the pleasure of discussing this thump with the designer. He ensured me that any normal, working woofer, would not be damaged by the turn-on thump in his amplifiers.
Later I have built quite a few different amplifier designs, and the only times I have built a turn-on thump are with single ended designs. None of the push pull-designs (that I built) have turn-on thump.
Some (working) pre-amps kan pass DC, some not. This is a design choice.
Power-amps can implement protection against DC in several ways, depending on the design goal of the power-amp. Simplest protection comes from a series capacitor at input. More complicated designs have circuits monitoring input and / or output for DC.
Looking at commercial offerings my guess would be that:
* professional amps have built-in protection
* high-power amps have built-in protection
* low-power, high-end amps probably won't have built-in protection
* older amps - you'll have to check