The purpose of an OD is NOT to add distortion. It's purpose is to hit the input of your amp harder and doing so changes the way the preamp react and sounds. If you play metal you will sound much better by using less gain on the amp and a stonger signal at the input that will saturate your preamp right at the start. The settings i described give tightness, a lot of attack and will also give you a more agressive tone. Because youy hit hard the front of the amp, it will also compress much more nicely. On the track Chaos will bring a new world it is my mesa R11750 with an OD in front. it is IMPOSSIBLE to obtain that kind of tone in the studio with a DR without an OD in front. It is one of the best thing you can do ti take your tone to the next level and is one of the best "secrets" kepts by professionals... I have already talked about it many times on this board, bands i know use or have used DRS in the past and did that (Metallica, Creed, Malevolent Creation, testament, etc...) I have work with many good Metal producers in Canada and all of them overdrived theirs amps in the studio and live. Andy sneaps who did Arch Enemy, As i Lay dying, Nevermore, etc.. Does the same thing... I even have an interview with kirk hammet who says that his secret weapon is is tubescreamer wich is ON full time in front of his amp. When i starded using an OD live with my Band, this is when people started complimenting my live tone... i'm not here to convince anyone, try it by yourself. People beleive the purpose of an OD is to add distortion, it can but it is not what it is made for, for that you should buy a distortion pedal