Can stereo pre-amp outputs be blown?

[trpower7]

I recently purchased a used car head unit, but can't seem to get any signal out of the pre-amp outputs. Is it even possible that all of these would blow without causing any damage to the rest of the unit?

[quiksilvia]

i have never heard of it, some decks have multiple fuses though, are they intact? the outputs can get loose and come disconnected, check hooking it up to mulitple amps with different rca's