The 970 is identical to the 1070 except for the removal of the amps. The only reason it might sound better would be the elimination of the 1070's amps from the chassis - that would get rid of the higher voltages required by the amp sections. It's not going to be anything significant, though.

The $200 in savings associated with the 970 over using the 1070 as a pre-amp wouldn't have any audible difference, but it might make your wallet find it prettier sounding.