This thread might be helpful on matching preamp and amps.
I'm also trying to sort this out. If you have amps with an input sensitivity of 2.15 Vrms, and a preamp with maximum output of 22 Vrms, would this not be a good match because you can only take use the first 2.15 Vrns from the preamp, and this would reduce your signal to noise ratio? So in this case, a low gain preamp would be a better mach to this 2.15 Vrms amp?