Harry Rivers wrote: Will an mp3 file be generally playable in 5; 10; 20 years time?

Almost certainly. It's much more likely you'll have lost the files, or cannot access whatever device you put them on, than that the mp3 format will not be decodable. mp3 is a proprietary format but its patents have now all expired. So there is negligible risk of somebody buying a patent and preventing people writing free software to access it. But it illustrates how old mp3 is - there are subjectively and objectively better formats.

If you're going to edit the recording it makes sense to take it off the recorder in uncompressed form - i.e. WAV. Otherwise you'll be uncompressing it, editing it, and re-compressing it again. Depends on having enough storage though.

And with storage much cheaper than it was when I started recording my vinyl onto mp3s, it's worth considering FLAC - which is an open (i.e. non-proprietary) format.

Harry Rivers wrote: This is my second attempt to reply but my first one disappeared.

My browser_tools might help there: it will recover a lost post - you don't have to use any other feature.