I honestly had no idea but I think I now know why one channel was always slightly louder than the other channel when playing vinyl on my turntables.
After watching this video I have the feeling that there must be millions of uncalibrated DJ turntables out there. A sad thought indeed given vinyl is often the audiophile's medium of choice!
You might have already know that anti-skating stops the needle from jumping out of the groove as easily. Scratch DJs usually crank the setting right up. What you probably didn't know is how to calibrate it correctly for every purpose.
Check out this excellent video for more.