Just a curiosity here... If you have a combo amp, with an extension output, this extension output is almost always wired in parallel to the speaker in the cab. If you then had an extension cab, which also has a "through" connection to daisy chain to another cab, this is also (almost) wired in parallel. Connecting the extension cab to the combo, whilst powering the cab from the combo, the extension cab also has an output that would connect another cab in parallel to the other two. If the amp in the combo was to die, would connecting another amplifier to the extension port of the extension cab basically run both cabs, or would having a dead amp (obviously unplugged from power) on the other end cause issues?