Is the Prologue Line Level?

[Automation]

Having some difficulty tracking with a particular preamp (presonus adl 600). It has instrument and line inputs. The manual states to use keyboards with the line level input but when I do so I get a barely (and I mean barely) audible signal. The instrument input works fine level wise but has grounding noise/ interference issues...Basically...this has got me pretty confused. I tried using a D.I. going into the instrument input but this again resulted in a very, very low signal level.

Any help would be great!