If your query was instead related to mechanical transmissions (often also called "trannies" in automotive circles), here are some technical "rules of thumb" found in recent documentation:
is a dual-channel equalizer known for its musicality and the specific way it models its output transformers ("trannies"). thumbs of trannies
The plugin features "headroom" controls for both input and output transformers. This allows you to drive the transformers into saturation for extra warmth and grit without necessarily increasing the overall volume level. If your query was instead related to mechanical