OT Question on audio downloads from youtube

[budge]

Please forgive the OT question but I am seeking advice on sensible 
download format for saving the audio from youtube videos which are 
available to supplement specific items from my early music collection.

My preferred solution is to download the audio using youtube-dl and I 
know I could then encode the file as a flac file but this creates huge 
files, albeit lossless, so my question is, is there any point in doing 
this if the initial audio quality is limited by the youtube video 
recording system bit rate?  Also, as a more senior citizen, I believe I 
am unlikely to be able to hear the difference between the flac and other 
options.

I know there are members in this group who have significant knowledge 
and experience in these matters and I am hoping for suggestions for the 
best format for my purposes.

Budge.