Hi Don,
Sadly, that PA80 was the last one to feature the guitar input. I really miss the option. The 800, 900, 3x etc all have stereo ins that work DRY as a line in, but if you want to use the harmonizer, the second input is rendered dead.
It's weird too, because when the 900 came out, the input did NOT shut off when a mic was plugged in, but the Korg people disabled that function with a quick OS update. Rumor on the street is because they wanted to make it MATCH THE MANUAL DESCRIPTION. Geeeze...