Perhaps the best feature of the Elekit TU-8300R 300B SE Tube Amp Kit is its ability to use such a wide range of output tubes without any modifications or bias adjustment. It is a tube-rollers dream. With that in mind we've assembled "Taster's Packs". Each package included two pairs of power tubes that are substantially different from one another. This power tube package allows you to compare the sonic differences and fine tune the amp for your own hifi audio system.