Re: Distortion pedal with smooth tone?
Not knowing what kind of budget you are looking for, I would recommend 3-4 pedals.
First off, I would say to set your amp up so that you are getting some overdrive from the tubes, then use and OD or distortion pedal to fill out the distortion and give you more bite, sustain, and harmonic detail.
In no particular order:
Brotech Fat Pipe Pro
Fulltone Distortion Pro
HBE Big D
Mesa Twin Valve