Marantz 8801 no sound, worth fixing or replace.

Last night during TV viewing all of a sudden the audio dropped to nothing, no blinking lights, no loud bang, pop or click, silence. All digital inputs produce a minor hum that gets louder as gain is increased. The pure/direct mode with analog inputs produces audio fine, but when I select "stereo" or any processed affect, no sound.
So sounds like something bit the bullet.  Love the sound of this unit for 5.2 50/50 movie 2 channel, not into more channels than that. My question is repair it or replace it?
Any advice or opinion is greatly appreciated.
Thanks
Steve