The AI preamp have a protection circuit that will not allow the unit to output if there is excessive DC at the output. I wouldn't worry about it. Just use the basic protocol. Amp on last, amp off first.
Do all tube preamps leak DC?
I want to pair an Audible Illusions L1 tube preamp with a Job 225 amp. Although both pieces have high gain, the gain can be reduced manually via two gain controls on the L1 preamp coupled with a master volume control. But here is my concern, the Job 225 amplifier has a Direct Coupled circuit that could potentially pass damaging DC leakage on to the speakers. So the question remains, do all tube preamps pass DC to one degree or another, specifically the Audible Illusions tube preamp?