I'll have to run down and copy my current settings from my TBR1-SL...not married to the rhythm tone just yet, but I like my clean setting.
These amps require a lot of effort to set up properly but the frequency response from the eq is nothing short of phenomenal, one little change makes a big difference. Also, cabinet choice seems to be particularly critical with Rivera amps. They do surprisingly well at low volumes, but once you crank them, look out they just spring to life.
The gain is there, but it doesn't sound like a rectifier. If that's what you're after then get a rectifier. My best description of the SL tone is that it fits squarely between a seriously modded marshall and a rectifier, it has it's own voice. Marry with that one of the finest cleans you will hear this side of a 65 deluxe reverb and that will give the basic idea. It sounds really full through a good 2x12, but pump it through a 4x12 and it'll darn near make you faint. I'm still figuring out how all the features interact with each other and the slope functions. Others who have good settings to try, please let us know, I'd love to experiment more. Oh yeah, these amps are so quiet it's eery. They do something with converting current to DC at certain points in the amp to keep the noise down...not sure exactly but I remember reading something about it...also not sure if they do that in all their amps or just the old TBRs.
Good luck and have fun.