Distortion/overdriven guitar

Ok so here my question...I haven't really known how I should set my amp settings...its a laney lx20,

My equalizer:
Bass = 5-6
Mid = 7-8
Treble = 9-10

My drive:
Crunch = ?-?
Master = ?-?

What should I set my drive to to get a good...

distortion sound...not to heavy but still enough...any help??prefurably papa roach meets thousand foot krutch type of distortion/overdrive

In my experience the only way to do it right is with an effects pedal. I have a multieffects pedal and it has loads of preset effects. If you cant get one though then try the crunch at around 6-8. The master volume control "shouldn't" effect the sound distortion.
The only way to really figure this stuff out is trial and error. Plug in the guitar, strum it hard at top volume and 'twiddle' the dial's until it sounds the way you want it. Have fun lad.