I'll say this, the more expensive QNAP desktop NAS's are incredible silent. .. but my newer TVS-1282, was quieter out of the box, than my modded TS-873 (Where I replaced all the fans, including the PSU's).

The other thing I highly recommend, is getting some anti-vibration mats, which massive help reduce the transference of HDD vibrations:

https://www.amazon.com/gp/product/B00HZS0CH6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

For me, these were a game changer... I side right beside my NAS and barely hear it.