I realise this is a pretty old thread...but I have exactly this problem and was wondering if a solution was ever found?
I have a guitar with Seymour Duncan blackouts and am using all outputs into my daw including spdif set to git/stack. Processed sound is fine; spdif out is set to -10db. The DI signal is crazy hot and distorting. Adjusting clean sens makes no difference, both the input and output leds are only green and my focusrite mix control is not getting into the red.
What's going on?!
Also - my output led flickers green even when the volume on the guitar is rolled off completely. What could be causing this?