The NX7 is brighter than the Spring 1, also providing better treble extension, resolution, and instrument separation than the Spring 1. At times the NX7's treble sounds really airy & sparkly at the same time it's amazing to hear. But then the NX7 may be a little fatiguing to listen to after a while and even harsh depending on your source. I highly recommend using a warm source to pair with the NX7. The cable included with NX7 is also really cheap and makes it sound harsher than it really is. The cable included with the Spring 1 is much better, I even started using NX7 with this cable.tell us more about comparison with NX7 please
I prefer Spring 1's mid range and bass performance. To my ears, the NX7 has a pretty lean mid range and the Spring 1 easily beats the NX7 in this area. Spring 1's bass hits harder & deeper than the NX7's followed by a slower decay. The NX7's bass is alright, it's got nice speed and decent impact but I like Spring 1's bass a little better. Overall, I think the Spring 1 is the more versatile IEM.
Soundstage-wise, I would say both the NX7 and Spring 1 have decent soundstage. Neither have holographic/huge/wide/tall soundstage like some TOTL IEMs on the market but I'm happy with both performances.
So to summarize my comparison:
Mids: Spring 1
Bass: Spring 1