You have rights to be cautious Audiolabyrinth about protecting your expensive poweramps, I agree get it in writing.
A tube pre if it's output is capacitor or transformer coupled gives some safeguard to precious large power dc coupled poweramps.
But if a tube pre is direct coupled and you get a bad tube or something goes haywire then your dc coupled power amps are in grave danger, even if the pre has output relays which can switch too late.
If something goes wrong, the dc offset in a direct coupled tube preamp premap can be up to 100 x larger that a transistor pre. Your poweramp may survive a dc coupled transitor pre going bad, but not a dc coupled tube pre.
Audiolabyrinth, George has no idea of what he is talking about here. I don't know of any tube preamp that is capable of doing the things he describes above, and that's after decades of making tube preamps with direct-coupled outputs. IMO he is trolling.
To put it more clearly, if the MP-1 did develop a fault, it could not make any high voltages as George suggests. We've been making the preamp since 1989 and FWIW it does not have a need for protection relays. It was designed to be fail-safe. To go 25 years like that should tell you something.
The preamp uses a patented circuit similar to what is used in our power amps. One of its advantages is that it is so reliable that it does need protection circuitry.
I hope that you understand that in order to stay in business, any manufacturer has to offer products that will not cause headaches down the road :)
I have already said why you will not find any manufacturer that offers 'documentation' regarding DC at their outputs. Put bluntly, the idea is preposterous.
IOW, George is wrong, this is not something you need to worry about. Its simply not an issue.
