My experience has been that playing a DSD file with convolution filter (DSP) puts the most stress on my CPU. The CPU processing speed will drop from over 100X for a typical FLAC down to something like 2.7X (on a NUC8i7). If you try to upsample to higher DSD rates it will even drop lower, but I never use that for listening. We put together some of these experiences in this thread.
In your case, the database is on an SSD drive which will help a lot (some other low-powered NAS don’t have that). You will also be temporarily vulnerable when you are loading a lot of new music to your database or when the database updates. But you are past the heavy duty database creation step.