[tomsem]

Yes, it will work, but only for .aax (Enhanced), not .aa (Format 4, which is about half the size). Only .aax format is supported by Kindle, it seems. (I have Kindle 8th gen, which just got Audible support and so it should also be same with Oasis).

This is baffling to me, since I suspect most people would prefer to conserve space in exchange for the negligible difference in audio quality. Moreover, .aax will not download in ‘parts’, whereas .aa will. But I think this was also the case with Kindle Touch, which was the previous Kindle supporting Audible (but you seem to have one, so you can verify it yourself).

The steps are (assuming your Audible and Amazon accounts are linked):
- go to Library page on Audible.com
- select ‘Enhanced’ Audio Quality
- click Download link
- connect Kindle and drag .aax file to /audible folder
- eject from computer

One cavaet: the one side-loaded .aax I tried had noticeable distortion when played at 1.25x or higher speed (maybe even at 1x speed - I would need to repeat the experiment to verify). When I deleted it and downloaded wirelessly this distortion went away. I don’t know if this is an issue with the download in question or would if it would affect all downloaded books. Certainly if it is the latter, it should be brought to Audible’s attention that the issue exists, it should not be so. I don’t have any requirement to side-load .aax myself, as it is far more convenient to download wirelessly (and you can start listening right away).

I may experience with a different book later on.

Is there some reason you prefer side-loading instead of WiFi? Or using a Kindle instead of a smartphone?

First impressions: it works better than I had expected. I don’t know that I’ll be using it much, however.