I'm not familar with your Rotel but integrated units sometimes have PREAMP RCA OUTS/IN with jumpers installed. You simply remove the jumpers and insert RCA cables on the PRE AMP outs and run those to the amp you'll purchase.
As for amp - are you looking for tube or SS? What speakers are you driving and what power requirements do you have?
As for amp - are you looking for tube or SS? What speakers are you driving and what power requirements do you have?