Hi Kinhoang: The tweeter should be at ear level when you are in your listening chair. My custom Sound Anchor stands are adjustable. Some of the bass boominess is sure to disappear after you lift the speakers off the floor. But you may still have to deal with acoustical null and peak room modes by, e.g., using wall treatments. I put treatments on the walls and ceiling. Also, play around with the low-frequency window settings in the crossover.
My electronics are quiet, but I have had noisy preamps in the past; and intermittent buzzing from a tube that was going bad. Make sure your tubes are quiet. And use hub- or star-grounding (both terms have the same meaning) with everything plugged into a central hub, and only one grounded plug going from hub into wall outlet.
Good luck