Might be something to do with using headphones, but you'll always have some sort of pick/finger attack, but it can be reduced. The way I achieve that really 'singing', violin tone (Eric Johnson is my go to guy for this tone), is by using a fuzz face style fuzz. With what you have, you might get closer by cranking up your distortion pedal into your already gain driven amp and then rolling the tone off at the guitar until you get where you want it to be. In short, more knob tweaking. If you place your compressor after the distortion (not the 'normal' way, I know) you might be able to set it up to add sustain without emphasising the note attack. Happy tweaking.