I have three QNAP NAS that I am using; two TS-932PX-16G and one TS-1679U-RP with 32G. Each one has 4-Drive SSD Caching enabled; the two TS-932PX units via their internal storage bays and the TS-1679U via a QNAP QM2 4-Port NVMe card. They are all connected to the same 10G fiber switch.