Is your audio hardware capable of high res playback? (External DAC etc.?)
When you specify the requirement of an audiophile level media player (software), are you using an external DAC/audio hardware that can support high res sampling rates or are you relying on the maximum decoding abilities of the internal DAC of the Neo X7 itself? (If you're simply relying on the DAC abilities of the Neo X7 alone you'll always be limited there regardless of which software media player you're using.)
Which aspect is your main preference? Audiophile level media player (local), or network capable as well?
You mean you'll connect your X7 to your receiver by 3.5 mm jack, yes?
In that case the Neo X7 will do the actual decoding & send the pre-decoded audio to your receiver. You'd need to use SPDIF or HDMI for audio passthrough.
As such, your audio will always be limited by the internal DAC of the Neo X7 so you really don't need audiophile level software without audiophile level hardware. Any half decent media player will do the job .