I would recommend an Xotic, also, but the BB Preamp. Separate treble and bass controls, you can use it as a clean boost or overdrive, depending on your needs. There is also the amazing Maxon OD-820, which as a tone control, but is essentially transparent. It can be used as a clean boost or OD, also.
If you're looking for something with more push, you should check out the Providence Sonic Drive.