Most overdrive pedals are built to stand alone i think. It's just a matter of how much gain you want and what kind of tonality you want. The reason why i say this is coz at least at one point in time, i've tried or owned the more common od models out there. Od3, ts808, od808, sd2, bad monkey to name a few and all of then sounded great at what they're supposed to do. Want transparent? Go od3. Want mid hump? Go for an 808 type. Want more gain? Buy a distortion pedal or a second od of the same kind to boost it. Wanna be broke? Get a zendrive... Hehe...