A few thoughts:
NAD C326BEE - lists for $550, but there's a factory refurb on the 'gon for $429 US right now. Nice solid amp for the money.
Never heard it, but there's also a Rega Brio 3 listed for $449. Some people really like it.
If you are willing to consider something completely different, there is an amazing deal on an open-box Wadia 151 Power DAC at Vanns right now. Normal MSRP is $1,195. You can pick this up for $599 US. This is a really interesting option. On the one hand, it has no analog inputs and no headphone jack, so it has limitations. On the other hand, the DAC is excellent and will likely offer an improvement over your older Rotel. For that price, I'd try it and return it if you don't like it. It has an exceptionally small form factor, which you may or may not like. It also uses Class D amps, which you also may or may not like. It could be underpowered (25W x 2 into 8ohms), but then again, the CNET reviewer (for what that's worth) said it was able to drive Magnepan 3.7s to moderately high volumes with great effect. If your room isn't too big and you don't listen too loud, this could be a really interesting option.
NAD C326BEE - lists for $550, but there's a factory refurb on the 'gon for $429 US right now. Nice solid amp for the money.
Never heard it, but there's also a Rega Brio 3 listed for $449. Some people really like it.
If you are willing to consider something completely different, there is an amazing deal on an open-box Wadia 151 Power DAC at Vanns right now. Normal MSRP is $1,195. You can pick this up for $599 US. This is a really interesting option. On the one hand, it has no analog inputs and no headphone jack, so it has limitations. On the other hand, the DAC is excellent and will likely offer an improvement over your older Rotel. For that price, I'd try it and return it if you don't like it. It has an exceptionally small form factor, which you may or may not like. It also uses Class D amps, which you also may or may not like. It could be underpowered (25W x 2 into 8ohms), but then again, the CNET reviewer (for what that's worth) said it was able to drive Magnepan 3.7s to moderately high volumes with great effect. If your room isn't too big and you don't listen too loud, this could be a really interesting option.