Micro SD Cards

@almarg 
Thanks for that post, al.
Regrettably, my SD card experience has gone from bad to worst.  The new card wouldn’t be read by the player as being correctly inserted.  In trying to remove it, the card has become so completely wedged in the tiny slot that I can’t extract it, even with a medical clamp.  It’s under warranty, but Sony is saying they won’t cover this.
This is my only experience ever with SD cards and it will be my last

I’m doubtful that the first card was actually ruined by formatting it in a Mac. My guess is that it was formatted into a "file system" the Sony can’t recognize, probably either the APFS or HFS+ file systems which are used by Macs of various generations.

And I’d feel fairly certain that the reasons Sony says to only format the card in the player are to allow it to establish the appropriate file system on the card, and to allow it to create a set of named folders that it is designed to work with when it is being used.

I’m also guessing that the Sony utilizes one of the many variants of the Linux operating system, and formats the card into an Ext4 file system.

What I suggest that you do first is to try to re-format the apparently failed card in your Mac, choosing a file system that is recognizable by essentially all modern computer operating systems, such as FAT32. Then see if the Sony can recognize the card and re-format it into its own format.

As far as being able to transfer files with the Mac on a card that has been formatted by the Sony, if I am correct in presuming that the Sony uses Linux and the Ext4 (or earlier Ext) file system I believe you would have to purchase and install the following program in your Mac:

https://www.paragon-software.com/home/extfs-mac/#

Regards,
-- Al

I’d rather transfer music on the Mac, where it’s easier to verify that the files are indeed on the card, or rearrange the order if I wish.  I’m just afraid that I’ll somehow ruin another card.  The Sony instructions say that the card has to be formatted in the player but are silent about whether the card can be removed to transfer files elsewhere, and the product support at Crutchfeld, from whom I bought the player, was useless

You could do it either way, the issue of music transfer often comes down to speed.