I need help with a edirol interface hooked to a blue tube

[feedback711]

ok, i got a edirol u25 interface and a presonus blue tube. i rum the mic into the preamp via mogami cables the preamp into the edirol and for somereason i still get a sound on the verge of distortion. i thought it was beacuse of the gains on the interface mixed with the gains on the pre amp but i have tryed every combination of settings including no gain on the interface. how can i get a clean signal. am i hooking it up right