I have been in the market for the older 80's model Yamaha amps. I really like the MX1000 or the M85. I have a friend that has the M45 and M85 but both have kicked the bucket recently. I know the amps were not abused at all. This makes me nervous. How durable are these amps? I know they are some of the cleanest (.007thd) and strongest amps (260x2) amps made that I can afford. Many are going up on ebay for decent prices. Who has experience with these older Yam amps and how do they compare to newer 2 ch discreet amplifiers?