The OD3390 Blues overdrive is tuned for those that like a little more headroom with a full sound that starts to breakup when pushed. You get both dual symmetrical Si diode and symmetrical MosFET + Ge diode soft clipping with the option of kicking in the symmetrical MosFET + Ge diode hard clipping. The slightly fatter mid-hump can be adjusted with the presence knob and you can get great clipping sounds like the Blues Breaker*, Timmy*, Morning glory* and that hard to find King of Tones*. Kick in the hard clipping and you get good sound without sacrificing too much output.
* names may be copyright of their owners and are not related to Witztronics. Sounds are similar, but depend on the gear being used.