1)The internal DAC of 9700 is much better than the DAC of Pro-Ject box and AV Amp, you may just connect the stereo output of 9700 with RCA audio cable to your AMP.
2)Connect the digital output of 9700 with coaxial cable to Asus E1 will be a good trial.
3)Always remember to plug the "8" type power cord to 9700 with correct polarity, it will affect the sound quality very much.
2)Although Asus E1 and 9700 are both using 2pcs same DAC chips for each channel, E1 is much easier to get better resolution and sound characteristic by replacing the opamps for I/V, LPF & buffer at the audio section.
3)The "Line" (火線) of the "8" type power cord should be at the right hand side while you look at the front panel.