Wow, you are trading one extremely old amp for another very old amp, but not as old. Hafler is 26 lbs for 115 watts per channel. Yamaha is 39 lbs for 170 watts per channel. Internal parts on the Yamaha are newer and the higher weight/power indicates a larger power supply, which could equate to smoother and fuller sound. But it's hard to tell with equipment from the 80s/90s.