The rest of your system is quite good. I think that you want to get as good of a source as you can and as good as the DacMagic is - and it will do a better job than the DAC in the RC-1072 - with the budget you are suggesting you can do better. There are at least two ways I think you can go:
1) a CD player that can function effectively as a DAC, like the Cambridge Audio Azur 840C - very good CD player and very good upsampling DAC with a nice array of digital inputs
2) stand alone DAC like the Benchmark you mention, and using your existing gear as transports. There are other more expensive DACs I would also consider, even if it means waiting a bit, like
-Bryston BDA-1
-Bel Canto DAC3vb
1) a CD player that can function effectively as a DAC, like the Cambridge Audio Azur 840C - very good CD player and very good upsampling DAC with a nice array of digital inputs
2) stand alone DAC like the Benchmark you mention, and using your existing gear as transports. There are other more expensive DACs I would also consider, even if it means waiting a bit, like
-Bryston BDA-1
-Bel Canto DAC3vb