I have 1604-Vlz3, M-audio Delta 1010LT With Cubase 5 . There is a main problem when it's normal with an apm it's no problem no sound problem but when the direct out is working with the sound card the sound is not ok. I want to know which QE setting is best for vocal . Because when the vocal is loud the Wave Graph is not ok & the the also is not ok what is the problem? if I Cut Whole mid sound And Hi 12K, Low 80hz,Freq- Set on FREQ mark. the is ok but sound quality is not so good What Is ur Preference Sir? MY Mic Is Sennheiser E845/Sure12A/SM56

You MAY be overdriving the sound card. Near flat should work for vocal, but setting the levels throughout the mixer is important as well as the sound card. You can use the LOW CUT to reduce hum if you have noisy system. Describing balancing the levels is more than I can do here. There are many good videos about mixer setup on YouTube.com. You cannot "fix" problems created by improper levels and noise injected into the system using the EQ.
What is important is to see that all gain controls and faders are around mid range to 70% when operating normally. You should be using BALANCED lines everywhere possible either XLR or TRS cables. ALL interconnected equipment should be powered from the same receptacle or power source INCLUDING all amps and powered speakers. Often users use unbalanced lines from mixers to sound boards and pick up noise or they have the levels set wrong between the mixer and sound board resulting in clipping and distortion or poor signal-to-noise ratio.