Scary said:
It's not hard, but it isn't easy either to do it right. My advice is to download the amps manual and read it over a few times at least. Tweak the amp at the volume you intend to play at live. I've had a Mark IV for years and with my setup I have to adjust the gain and channel volumes to get them to play along together. The tricky part can sometimes be getting your FX to work without killing the tone. There is a minimum level of signal that needs to be maintained or the tone falls apart. Good luck.
As with any channel switching amp - yes you have to find the balance between the channels that work for you.
Personally; I set up my master output with the R2 Master FIRST for the venue we are in. And then I set up R1 Master and then Lead Master. I set up the EQ to give me a solo boost on all three channels.
I use generally R1 for: 50's, 60's, Motown, and country music,
R2 for my normal distortion sound; such as AC/DC, Def Leppard, Blondie, etc
Lead heavy distortion for metal etc.
Using the EQ as boost I can have a solo boost with any channel.
I do alot of volume control using the guitars volume knobs and I can get alot of different sounds with pickup selection.
After using the amp for so long I really don't touch the other knobs much any more. Maybe the presence sometimes.
No pedals, no processors.
The Mark IV is remarkably versatile. It can cover a lot of ground.