The Red Rooster Booster adds about 33db of guitar-friendly, unbuffered boost to your signal. That’s about the same as adding a preamp tube stage to your amp. The RRB intentionally adds more gain in the upper mids (your guitar needs it to cut through a mix!) while also adding some presence to keep from turning the sound murky.
This was Ken Fisher’s favorite booster and he even built a Trainwreck amp to work perfectly with it (named Songwriter, the one Brad Paisley records and tours with). Ken likened the Rooster variations to swapping out different brands of preamp tubes.