Humming noise Problem on the inputsignal

Hi There, need some help

i own an effect unit from Ensoniq the Dp4. I have problem with the input signals, there is completly distorted a lot of hum and noise.
i did a check after the D/A converting and the effects blocks. on the signal path after the effect which is going to the outputs everyhing is okay because i can generate i sine wave signal in the effect processor and it sounds good.
What are the possibilties of these issue ?

Grounding?
a faulty Tl074?