If the Bluetube has a 1/4 inch instrument input, it is acting as a DI, and you wont need another. Well, you might NEED another, but thats beside the point Keep in mind that it sounds best when the tube is, indeed, blue. Makes a huge difference.
Why in the hell, or how in the hell, is your avatar so huge? EVERY time I find something I want to use, it wont let me cause its too big, and I never even try ANYTHING half that size. Weird.