Boosting treble and bass SHOULD raise the overal level (possibly requiring you to turn down the volume knob), and leave the mids at the old level, giving the 'smiley face' EQ you want.

One thing to note is that different companies pick different frequencies for the 2 band tone controls. On a 2 band tone control, often the frequency of Max boost-cut is specified. For instance if the frequency of the treble knob is 10 KHz, then if you boost, the frequencies from 10 KHz up to 'as high as you can hear' are boosted flat, and there is a smooth line connecting the midrange no-gain point, rising up to 10 KHz max boost. Same deal for cut.

Different folks have ideas on what is the most musical bass and treble max-gain boost. Mackie for a long time used 50 Hz for bass and 10,000 Hz for treble. Peavey for a long time used 100 Hz for bass and 5,000 Hz for treble.

If listening in a 'squeaky clean' environment with very wide range speakers, some folk liked the Mackie wider settings better. But IMO, in a practical situation, the Peavey narrower settings seemed more generally useful. For instance, most 'audible' bass is higher than 50 Hz, so if you really need a good boost around 160 Hz on a track, with the Mackie tone controls you would have to suffer with 'too much' boost down in the rumble territory, to get the 160 Hz boost you wanted.

Maybe the specs of the speaker you want would publish the tone control frequencies. Or maybe not.

James Chandler Jr
http://www.errnum.com/