HK avr 80 - turns on, display lights up, but NO Sound!?

I just purchased this receiver used -

The power turns the unit on, the display lights up,

I hooked up the 5.1 speakers correctly... but no sound.

I've already tried to reset the receiver by pressing memo & clear - simultaneously - no no avail - still no sound..

* I believe another user documented the phantom phenomena- the unit turns on automatically, & goes to TV'

I just want sound - any tips or am I missing an important step - like resetting the jumpers somehow?

Help!?