There was a certain BAT tube preamp that had a problem and was putting out DC into amps. I've been running a tube preamp into a krell ksa300s for about 5 years now with no problems.
Audio research and krell
So here goes I have a arc ref 5se and I am using a krell Kas 300s and recently I noticed the krell was making some noise when powered off so I made some calls to krell and found out that the older krell amps are not recommended to be used with tubes I have never heard this .so has anyone here heard this .second question if that's the case what should I move to for a new amp I like the krell sound. Speakers are revel salon 1 transparent cables