In fact I don't need 4 hard drives, because my understanding is that the QNAP should be dedicated to Sooloos and/or Roon only, then no picture, docs, storage ...

I was thinking that having a less powerfull QNAP but having a NUC to handle Sooloos and Roon would be better.

G65, 598DP, UHD722, DSP5200SE Front LR&C, Cable TV, Pioneer Kuro LX509