Sansui BA 3000 amp and CA 3000 preamp question

HI everyone, I am a newbie to this forum- don't know why it took me so long... When I moved to Mexico 24 years ago, I made one trip with a motorhome just to transport my audio equipment - too many pieces to list. The guts of the system are two Sansui BA 3000 amps run mono through a CA 3000 preamp, all into two Cerwin Vega D 9's rated at 4 ohms each. This all ran ok with wonderful sound for several years in Canada. After several years in Mazatlan, Mexico ( yes, on the ocean, and we have salt air) one amp gave up, and I continued to run the other amp stereo through the preamp. Still sounded good, but definitely lost some punch.

Then the other amp lost a channel.

Everything went into storage bags, and I was forced to add an Onkyo receiver to power things ( the best thing I could find new down here) Definitely does not do the speakers justice. I am now going to deliver the three units to a reputable repair guy in Tucson for refurbishment. The question I have is: I just looked at everthing inside, and don't see evidence of major corrosion or deterioration; but did notice a sticker on the back of the amps indicating mono(340 watts) into a minimum 8 ohms. DId I damage these by powering the 4 ohm Vegas, or are they stout enough to handle the lower ohms? Other than repair, would I be better to get a reconditioned big power Adcom or like amplifier that is designed for lower ohms? Thanks in advance, Steve

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