Hi Laura,
If your Denon won't output a test signal, I fear that the lightning strike may have damaged the microprocessor in the preamp section. You could confirm this is you have any old stereo amplifier or receiver kicking around that you could hook up to the Denon's pre-outs for the left and right front channels. If the one channel and test signal were still not functioning then the damage would be in the Denon's preamp section.
If it's any consolation, my otherwise excellent Oppo DVD player just stopped reading DVDs and DVD-Audio discs. It still plays CDs and SACDs but not DVDs. Most annoying.
Equipment does fail on occasion.
Denons, NAD, B&K, Sherwood Newcastle, Rotel and Outlaw Audio will unfailingly drive M80s, even their entry-level models. I'm less confident of Onkyo, Pioneer, or Yamaha with the exception of a few high-end models that some Axiom forum members say will drive the M80s without shutting down.
Regards,
Alan
