[dmitrygr]

> WARNING: A tube amplifier chassis contains lethal high voltage even when unplugged--sometimes over 700 volts AC and 500 volts DC.

I promise you it does not contain AC when unplugged :)

[bogomog]

But capacitors may hold high voltage DC, if there's no path to discharge them.

[kragen]

Nope, probably not at all, and certainly not for very long.