Looking for advice on a rack mounted NAS option that can do 4k transcoding, minimum of 4 bay with expansion potential with a max budget of $2K
There are quite few options among Qnap product range. Have a look at ts-453du,ts-453bu. These models come with a PCIe allowing easy expansion or 10GbE upgrade. Using Video Station app you will be able to transcode even 4K.
I hope this helps.