A dependable starting point is Level 6, Tone 5, Drive 4. As an amp booster keep the Drive low and the Level high; as a standalone overdrive push the Drive to 5–6.
What is the difference between the SD-1 and a Tube Screamer?
The SD-1 uses asymmetrical clipping and is a little brighter and more open, with slightly less of the Tube Screamer's pronounced mid-hump. Both work superbly as low-gain boosts to tighten a high-gain amp.
Recommended starting points are community-researched estimates — every pedal, amp and guitar is different. Dial from here, then GuitarToneAdapt helps you match a target tone on your own rig. Pedal comparisons · Amp settings · All tones