Audio Research made the biggest change/advancement in the mid/late 80's with their solidstate-and-tube designs, for both amps and preamps, better know as "hybrids." A perfect example is an M300 MkII I have for sale on the Gon right now. This vintage and later are easily repairable and upgradeable but the earlier ones sometimes present parts matching difficulties (depending on the part) Usually tubes are not a problem.
As far as measuring up to todays' standards, the early ones, no. Mainly because component parts have improved so much. Later ones can be upgraded where it counts (which ARC is happy to do for a price!) and can be made to come pretty close.
As far as measuring up to todays' standards, the early ones, no. Mainly because component parts have improved so much. Later ones can be upgraded where it counts (which ARC is happy to do for a price!) and can be made to come pretty close.