tube pre amp and Krell FPB 600

^^Even if you have solid state you can get a thump. The reason you don't is your preamp has an automatic mute.

Many tube preamps do nowadays too.

I always get a thump sound over the speakers when I turn my amp off, it's really alot of power, seems normal to me.

I've had 3 Krell amps over 10+ years and always drove them with tube preamps (SF, McIntosh, CJ ...) and never had a problem.

There are reasons for rules. If not followed, probability of problems increases.

I leave my SS amps on continuously per the manufacturer's instructions and get a thump through the speakers when I turn my tube pre-amp off. This is normal according to the manufacturer. There is some woofer excursion but not as great as it is when playing at very loud volumes, so I don't worry about it.

12-04-14: Audiolabyrinth
I always get a thump sound over the speakers when I turn my amp off, it's really alot of power, seems normal to me.

Hi Audiolabyrinth
As explained by Krell to me it’s a small amount of DC that escapes through the outputs as the relays shut down. Not hazardous to speakers.

My Krell amp makes a very subtle thump at shutdown only too. My previous OTL monoblocks would do it at startup and shutdown. The Classe amps were both startup and shutdown but only occasionally. The others I owned like multiple Bryston amps, and others I demo'ed like Pass Labs and others I can't remember. My Roger Modjeski Rm9 and Rm10 tube amps do not do it.

Cheers