DC issues using a Krell KSA 150 w/ tubed preamp?

There is no such thing as 'tube DC'. No preamp, tube or solid state, will make DC at its output if it is working right.

IOW, the idea that tube preamps have DC at their output is a myth.

I think the "working right" is the operative term. Tube failures are not uncommon.

Unsound, even if there was a tube failure, DC would not be the result. DC would be the result of a coupling capacitor failure, something highly unlikely in a tube preamp, as said cap would be a film type, which are very stable parts that last decades.

If anything, the electrolytic caps common in solid state preamps are far less reliable!

IOW, what we are talking about is indeed a myth

Not true Atmasphere, your amps may be of a better quality but I experienced a reasonably high DC offset on a modern preamp that retailed 8 grand; the coupling cap was indeed the culprit. So always measure with a VOC meter which can be had under 20 bucks.

Atmasphere explain that to C/J. I just got done working on a Prem140 that had Polystyrene film caps at the input and output of a 440Vdc regulated power supply. Every single semiconductor device including 15 zener diodes failed dead short because one of those film caps instantaneously shorted and healed. I've also had to replace coupling caps in McIntosh and Dynaco amps and preamps due to either shorted or leaking coupling caps. It happens far more often than you think, especially in older gear.