ide hook a different amp (even an integrated if you don't have another power amp)to the speakers or different speakers to the amp to see which is not performing. my guess is either the connection between the power amp and speakers or the power amp itself. the preamp (and the link to the power amp)is good since the power amp gets signal and there is sound through headphones.
Help with hookup
Inherited some audio equipment. Hooking up a McIntosh mc2300 preamp to a McIntosh mc352 amp to a pair of Acoustic Zen Adagio speakers, but I don't get sound out of the speakers. I can hear when I plug in the headphones, so there is that. Any ideas?