Well, the buffer controls the latency (delay) of the program, which in affect effects your scratching. Though the latency doesn't make them sound "distorted," that sounds more like a calibration/estimate slider issue.

I would agree with Konix. Try recalibrating your setup.

Remember.. this needs to be done every time you move to a new location.
After calibration, the number in the upper right corner of the scope view in the setup screen should say 0.0 while the needle is on the record and the turntable is stopped.
If that number is fluctuating than you need to manually move the threshold slider to the right until that number is stable at 0.0.
If you've moved the slider all the way to -24 and its still fluctuating than you have a grounding/interference issue somewhere in the chain.
If this is the case first make sure that your turntables are grounded.
Next try to make sure that the SL1 interface isn't sitting next to a power source such as a power strip and that the cable coming to and from the SL1 interface aren't being laid across anything that conducts power.

Hope that helps;)

Try Hi Fi in the setup, if calibrating doesnt work