You said "i have some great old PSB Gold Stratus speakers (4 ohm/250 program) powered by a Rotel amplifier" so I assumed you have already been using the Rotel with those speakers already, and since the RB-980BX is just a power amp, so you must have some sort of preamp or receiver to drive it right? That's why I asked what (that is, the kind/model of preamp, receivers etc..) were you driving it with. Sound like there is some misunderstanding on my part..
Regardless, most mid range AV receivers such as the Denon I suggested, can almost match the power output of the RB-980BX. So if you have already used it to power your Stratus Gold then you should be fine with the AVR-X3400H or comparable Marantz, Yamaha receivers, though I doubt you would be getting the best of the speakers using the not very powerful Rotel amp, unless as I mentioned before, you sit very close and don't listen very loud at all.
Based on available bench measurements, I do think Denon or Marantz AVR's preout are more capable then Yamaha's. However, if you stick with power amps with gain higher than or at least 29 dB, the Yamaha RX-A1080 or higher models should be fine, for power amps rated up to 200-250 WPC into 8 ohms.