Looks to me like your issue after all is more semantical than technical and generally about persistence of files in e.g. /etc...
We may simply have to accept differing views on this. My interpretation of persistence is the one given in the Core Concepts document which has been my reference.
Backup/Restore and Other Persistence Options:
...Tiny Core supports persistent/permanent:
Backup and Restore of personal settings, and
Persistent /home and /opt directories.
I feel this is indicating a difference between backup and persistence. Backup is used to preserve the data in volatile storage areas between boots as the file and directory structure is destroyed at the end of the session. Persistent storage is not destroyed but remains unchanged and available at the end of the session. They are different mechanisms of ensuring the continuity of data depending on whether the storage is volatile or persistent.
My understanding is that only /home and /opt can be persistent in this way unless the hybrid/local install method is used.
...
When using the home boot code, mydata.tgz is not created - personal data backups must occur in a more traditional way.
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This reflects my situation, the bootcode is used and persistent /home is created.
If this works, perhaps it might be added to the notes in alsa.tcz
I can't see why this shouldn't work and after reading the info of alsa.tcz once again I respectfully disagree with upper suggestion, as the instructions are very generally worded and IMHO giving examples of implementation for particular scenarios within an extension .info would rather lead to confusion than to clarification.
The guidance in alsa.info will work as described for those using volatile storage alone as filetool will be used to create a backup. The advice is less suited to those implementing the guidance in Core Concepts referring to persistent storage and backups. The suggestion to amend alsa.tcz is intended to help this latter group.
It is good to have different opinions expressed; after all that is what a forum is all about. Thanks for your suggestion to use
alsactl restore as it had not occurred to me. As is often the case there can be many ways to resolve a problem and your input helped.
...You could just an easily specify only those non-persistent areas as shown in the .info file to have persistence and backup. Alternately you could make a tiny custom my_alsa_setting.tcz extension.
Yet more examples of the multiple ways to resolve an issue.