For what its worth, I've had the Core 7s, together with an 18s Subwoofer for a while now and I'm very happy with them. I used a UMIK-1 measuring microphone:
https://www.minidsp.com/products/acoustic-measurement/umik-1 and REW:
https://www.roomeqwizard.com/ to generate room correction PEQ settings and I think they sound great, I like the look of them too,
but bear in mind, I have not compared them to any of the highly recommended monitors from the likes of Genelec, Neumann, etc.
Regarding the hiss, I have the Core 7s nearfield, about 1m from my listening position, and when I first set them up the hiss was quite noticeable, but by lowering the input sensitivity I was able to reduce the hiss such that I can no longer hear it, see here:
https://www.dynaudio.com/professional-audio/core/core-7/support/manual/en/adjusting-the-volume