Here's some 7 string riff sounds, I started to love these once I mixed and matched instead of using the same impulse on both tracks. I just used my Van Halen preset with nothing but chorus and EQs on the left track and EQs off for the right one.
https://soundcloud.com/tltd/rosen-digital-voxac30-2x12-cab-w11r-jackson-js22-7