Actually, the two masters are not for each individual channel. Both masters control both channels. Master 1 for normal rhythm, Master 2 for the boost.
If you want more volume out of your channel 2, turn up the channel volume on that channel. I run my channel 1 voume at noon, and my channel 2 volume about 2:00. I was a little confused at first, too.
You may also notice that the tone opens up a little brighter when Master 2 is engaged. I actually like to use Master 1 and Master 2 (with similar volumes) as separate channels, and just use channel 2 for leads. Especially since you can adjust the channel volume acordingly for the boost (without even using the Master 2.
There are many different ways this fine amp can be utilized!
Brian