Yep.... since you tried the things suggested and still have distortion, See if you can borrow a DI box and try it. If you don't know anyone with a DI laying around, just pick one up from Guitar Center or Sam Ash and try it. If it doesn't work, carry it back for a full refund.

Your signal level is too hot from the keyboard and there's also very likely an impedance mismatch that may be a contributing factor.... a good DI box may just solve that problem.... it's worth a try.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.