+1 to @russ69
Without prejudice to his post merits, be also cognizant of the fact the “vintage” just means “old”. Old amps all suffer eventually from unavoidable, necessary, and expensive upgrades for failing capacitors et al. Some units can no longer be repaired today because replacements for failed old model printed circuit boards first introduced back then, are no longer available.
A local tech just told me that he just had two instances of failed “vintage” KRELL amps that now fall into this shitehole for their stunned owners.
CAVEAT EMPTOR: In his words, they are now “ boat anchors”.