I have a Line 6 ModPro, the rackmount version, and a Yamaha Clavinova keyboard (model CLP-511). I tried hooking the Line 6 effect box through the Auxiliary in/out only to get major noise. Just a beastly ringing that sounded like somebody threw all the volume knobs to unity gain. Does anyone have any idea as to why this happened? Or better yet, how I can hook the Line 6 up to my digital piano, if it's even possible?

It also has a headphone output...could this work? Or would I just be in for more squelching and screaming from an amplifier?

Did you try just taking the main analog out of your keyboard and plugging it into the input of the Line6, then out of the Line6 into your amp (or headphones)?

That should work...

Good question Shack- I'll look more info for you 'cause now I'm on the mission as they say

That's the thing...It's a digital piano so it has internal speakers. I can't just take an analog out, sadly. =(

It COULD just be incentive to go out buy myself a Nord...ya know...maybe...