You should connect the outputs of your SL-3 into line level inputs on your mixer. Make sure the toggle switch for each channel of the mixer is set to line.

On the screen below each virtual deck is a THRU button. You want to unhighlight it to hear sound coming from Scratch Live.

Put a song on the virtual deck and put it into INT mode. Press play on the screen and after doing the above, you should hear it.

hello i need some help with my cdj 800 mk2 and ssl3 i have my cdjs set in abs mode everything works fine except for when i try to loop when i hit the 4 beat loop feat. it loops but not seamless you can tell that its looping or it seems like the cd is skipping over and over why doesnt it loop seamlessly? whether i use 1 beat 2 beat 4 beat or 8 beat they do the same its not seamless help please thanks

The CDJ doesn't know the bpm of your music file - all the CDJ is 'hearing' is the constant drone of the timecode CD. So it can't tell what length a 4 beat loop should be, and it's basically just doing a random loop.

If you want to use loops with Scratch Live you need to use relative mode and use the loop facility in the software.

The BPM of the song needs to be accurate for it to place an accurate loop as well.