SMSL SU-9 DAC

This is correct. MQA was developed not necessarily to add quality, but specifically to add DRM. In essence, it is just FLAC with applied digital filters, though usually, because it is "tuned up" to the human ear perception MOA sounds better than old plain vanilla FLAC at the same resolution. When used thru digital streaming services (like Tidal, etc.) MQA is worth it IMO since it frees you from applying your own digital filters, but if you are buying files to build your own musical library MQA is superficial and very inconvenient to have actually.