With all this drama surrounding SD cards not being able to handle what the MixPre is capable of:
1. Is it possible that a good amount of newly produced flash media are simply not up the performance challenge of multi-channel, high-bitrate / depth audio?* I think we can all agree at this point that the manufacturer speed rating of the card seems to mean little when it comes to audio applications, as has been proven time and again. Remember that the 7-series used CF cards, hard drives, and SSDs. I don't recall any drama about write problems.
2. If (1) is true, then why (other than cost) are audio recorder manufacturers still using this format?
3. If I was working for Sound Devices, I would have ditched the SD card slot in series II, and instead used m.2 NVME SSDs. They are small, relatively inexpensive, and their read/write performance is superlative. The recorder would probably never approach the limits of what that SSD could handle, but then you would be assured that you would never run into a media performance bottleneck.
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*Alternate theory:
Could audio recorder manufacturers simply be using write buffers that are too small, as was speculated with the Tascam media performance issues?