Hello everyone, 
I currently own the 530 integrated and recently decided to replace it with the 711.  As the 711 arrived a few days ago , I had the chance to use the preamp from the 530 ( which is basically the 520) and connect it to the 711. The differences were immediately apparent. Much more authority and differentiation  in the bass region. Increased volume of the sound, more space from left to right and front to back.  The sound was  more transparent as well. The 5 series  amps  are truly great but the 711 is a  big step up. I have no doubts now that  it has to be paired with the new 7 series preamp to properly deliver.  The high bandwidth amplification system , high storage capacitance and extreme slew rate are concepts shared both by the 711 and 725. Again the 520 preamp sounded very well already but given the change brought by the 711, the 725  will truly reveal  what the 711 is capable of. 
Regards Martin