It's very important to try and see if any perceived lack in bass or treble isn't simply due to one or more of the Parts needing EQ, rather than the whole thing. I often hear boomy pianos, or tinny cymbals on people's demos, and can usually put the blame on Master EQ set to make the drums and bass deeper, or the guitars brighter, whatever, whereas simply fixing the REAL cause of the problem doesn't actually make other things worse...