Amp comparison

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.

Hafler! A great classic amp designed by Erno Borbley (who also did all the SS gear for the company). I have a nice pair of the 110 preamp and 220 in my collection! 

The Hafler 220 is no Model T! It is still competitive sonically with much pricier amps of today! A classic MOSFET design!

I’d skip both. I used to work for a company that kept Hafler in business buying amp modules. In direct comparisons to other amps, driving high efficiency theater (auditorium) speakers, I always found them weak sounding.

Not to mention it's time for them to be recapped.