good sound from art rack

Should I set the input or output levels so that i nears the red lites-0dB?
Actually how should I set up from the guitar to the fx proc.(ART) to a Yamaha md8 to tower records? ok forget the last part.
Red lights usually indicate "Clipping" (distortion) . You may need a pre-amp to get a good signal into the ART. My Art FXR works best when I run it from an effects loop (when using a Guitar amp) or from an effects send from a mixer board. That way I don't have to turn up the input so high. This keeps the signal cleaner. Watch that clipping light.....I hope this helps?

Dom Franco