Just got a Carvin 4 string active/passive electronics. When using the active setting, is it wise to flatten the highs/mids/lows or use the detent. I'm tired of lugging my amp around. I'm thinking of going into a powered mixer via a Radial Passive DI box..XLR channel. If I go this route, I like using 12" speakers or shall I use EV 15" ZX4's? Lastly, what does the toggle switch on the bass activate. I'm new at this..thanks.