Sound preference is quite personal. I would suggest you also consider:
- dp-x1 has 2.5 balanced output, x7 doesn't
- the Music app is by Onkyo, x7 doesn't have it's own player app if I am not wrong.
- dp-x1 has not only EQ , but Lock Range, Digital filter, Upsampling , all are ways to tune the sound. I don't think x7 user has that many ways to the sound.
- dp-x1 has 2 dac, 2 amp. x7 has only 1 dac 1 amp. Even the LO output, dp-x1 can use two dac for dual mono design.
This is a really misinformed biased comparison...
- X7 has swappable amp modules, there is a balanced module which can provide balanced output (as well as other swappable modules)
- X7 has its own Fiio-designed player app.
- Fiio X7 uses the desktop sabre dac which has capability for 8 channels, whereas DP-X1 uses 2x stereo dacs. It's not simply a counting game.
- DP-X1 can only use dual dac and dual amp in balanced, and only uses 1 dac 1 amp for SE.
- You can't "use 2 dac for dual mono design", dual mono design refers to the circuit design. A device is either a dual mono design, or it is not.