Question. You say ‘SD card’, are you actually speaking of a USB thumb drive ‘stick’ mounted to the USB port in the rear of the N200?
The N200 has two drive bays for two separate 2.5” hard drives, which I would highly recommend utilizing in lieu of a ‘flash drive’. 4TB 2.5” drives are fairly inexpensive today, and the N200 will accept two 8TB drives. That said, the rear USB port can be used to mount an external hard drive, or ‘thumb drive’ too, so I would think Aurender engineered that port to sound as good as any internal drive you install into its drive bays.
Thus, have a feeling whatever drive was included with the N200 (assumed from a third party) may have been compromised, as previously mentioned.
Ripped files (given a high quality rip) should sound every bit as good as streaming, if not better in some/most instances (DSD or HiRes PCM files).