YOu could and many use them in combination. Not always with the Hydra, but the Monster does not clean power but just regulate the voltage at a steady 120. You then plug whatever power conditioner into the Monster to get both conditioning and regulated voltage.
I had this actual combo at one time. My voltage did not prove to be an issue so I saw no sense in using the Monster. The Monster also proved to be a chock point in my system and sounded better when I bypassed it. Now If I had terrible voltage, maybe It may had improved my system??? Others seem to get improvments on it.
