Best Used Amps. for Infinity RS-1B Speakers

IMHO, it would be best to use identical amps that are extremely stable into a 4 ohm load, and more power than you are currently using. Do you have a budget?

In my system I use two (2) Mac 275 ver 5 on the top and a Perreaux 3150 on the bass. I am very happy!!!

RWD

Lots of choices really. Some of it will depend on how loud you want to play, the RS1Bs need some power. The 120 watt Brystons are going to run short of power. I run my woofers with a Parasound A21 that's a nice cheap amp that sounds good. I have also run EMIMs with that amp and that works as well. The solid state CJs have a nice tonal quality and if you don't play too loud even a nice tube amp will run the mid panels. EMIMs sound nice with tubes.
What pre-amp are you using?